There are six factors that prevent [a priest] from reciting the priestly blessings: [an inability] to pronounce [the blessings properly], physical deformities, transgressions, [lack of] maturity, intoxication, and the ritual impurity of [the priest's] hands.
[An inability] to pronounce [the blessings properly]: What is implied? Those who cannot articulate the letters properly - e.g., those who read an aleph as an ayin and an ayin as an aleph, or who pronounce shibbolet as sibbolet and the like - should not recite the priestly blessings.
Similarly, a stutterer or one who speaks unclearly, whose words cannot be understood by everyone, should not recite the priestly blessing.
אשִׁשָּׁה דְּבָרִים מוֹנְעִין נְשִׂיאַת כַּפַּיִם. הַלָּשׁוֹן. וְהַמּוּמִין. וִהָעֲבֵרָה. וְהַשָּׁנִים. וְהַיַּיִן. וְטֻמְאַת הַיָּדַיִם. הַלָּשׁוֹן כֵּיצַד. הָעִלְּגִים שֶׁאֵין מוֹצִיאִין אֶת הָאוֹתִיּוֹת כְּתִקּוּנָן כְּגוֹן שֶׁקּוֹרִין לַאֲלֵפִי״ן עַיְנִי״ן וּלְעַיְנִי״ן אֲלֵפִי״ן אוֹ לְשִׁבּלֶת סִבּלֶת וְכַיּוֹצֵא בָּהֶן אֵין נוֹשְׂאִין אֶת כַּפֵּיהֶן. וְכֵן כְּבֵדֵי פֶּה וּכְבֵדֵי לָשׁוֹן שֶׁאֵין דִּבְרֵיהֶם נִכָּרִים לַכּל אֵין נוֹשְׂאִין אֶת כַּפֵּיהֶן:
Physical deformities: What is implied? A priest should not recite the priestly blessings if he has blemishes on his face, hands, or feet - for example, his fingers are bent over, crooked, or covered with white spots - for they will attract the people's attention.
A person whose spittle always dribbles when he speaks, and also a person who is blind in one eye should not recite the priestly blessings. However, if such a person was well known in his city and everyone was familiar with the person who was blind in one eye or whose spittle dribbled, he may recite the priestly blessing, for he will not attract their attention.
Similarly, a person whose hands were colored purple or scarlet should not recite the priestly blessings. If the majority of the city's population is involved in such a profession, he is permitted, for this does not attract the people's attention.
בהַמּוּמִין כֵּיצַד. כֹּהֵן שֶׁיֵּשׁ מוּמִין בְּפָנָיו אוֹ בְּיָדָיו אוֹ בְּרַגְלָיו כְּגוֹן שֶׁהָיוּ אֶצְבְּעוֹתָיו עֲקֻמּוֹת אוֹ עֲקֻּשּׁוֹת אוֹ שֶׁהָיוּ יָדָיו בּוֹהֲקָנִיּוֹת לֹא יִשָּׂא אֶת כַּפָּיו לְפִי שֶׁהָעָם מִסְתַּכְּלִין בּוֹ. מִי שֶׁהָיָה רִירוֹ יוֹרֵד עַל זְקָנוֹ בְּשָׁעָה שֶׁהוּא מְדַבֵּר וְכֵן הַסּוּמָא בְּאַחַת מֵעֵינָיו לֹא יִשָּׂא אֶת כַּפָּיו. וְאִם הָיָה דַּשׁ בְּעִירוֹ וְהַכּל הָיוּ רְגִילִים בְּזֶה הַסּוּמָא בְּאַחַת מֵעֵינָיו אוֹ בְּזֶה שֶׁרִירוֹ זָב מֻתָּר לְפִי שֶׁאֵין מִסְתַּכְּלִין בּוֹ. וְכֵן מִי שֶׁהָיוּ יָדָיו צְבוּעוֹת אִסְטִיס וּפוּאָה לֹא יִשָּׂא אֶת כַּפָּיו. וְאִם רֹב אַנְשֵׁי הָעִיר מְלַאכְתָּן בְּכָךְ מֻתָּר לְפִי שֶׁאֵין מִסְתַּכְּלִין בּוֹ:
Transgressions: What is implied? A priest who killed someone should never recite the priestly blessings, even if he repents, as [implied by Isaiah 1:15 which] states: "Your hands are full of blood," and states: "When you spread out your hands, I will hide My eyes from you."
A priest who served false gods, even if he was compelled to do so or did so inadvertently - though he has repented - may never recite the priestly blessing, as [can be inferred from II Kings 23:9, which] states: "However, the priests of the high places shall not ascend [to God's altar in Jerusalem]." [The recitation of the priestly] blessings is equated to service [in the Temple], as [Deuteronomy 10:8] states: "to serve Him and to bless in His name."
Similarly, a priest who converted to the worship of false gods - even though he repents - may never recite the priestly blessing. Other transgressions do not prevent [a priest from blessing the people].
גהָעֲבֵרָה כֵּיצַד. כֹּהֵן שֶׁהָרַג אֶת הַנֶּפֶשׁ אַף עַל פִּי שֶׁעָשָׂה תְּשׁוּבָה לֹא יִשָּׂא אֶת כַּפָּיו שֶׁנֶּאֱמַר (ישעיה א טו) ״יְדֵיכֶם דָּמִים מָלֵאוּ״ וּכְתִיב (ישעיה א טו) ״וּבְפָרִשְׂכֶם כַּפֵּיכֶם״ וְגוֹ׳. וְכֹהֵן שֶׁעָבַד כּוֹכָבִים בֵּין בְּאֹנֶס בֵּין בִּשְׁגָגָה אַף עַל פִּי שֶׁעָשָׂה תְּשׁוּבָה אֵינוֹ נוֹשֵׂא אֶת כַּפָּיו לְעוֹלָם שֶׁנֶּאֱמַר (מלכים ב כג ט) ״אַךְ לֹא יַעֲלוּ כֹּהֲנֵי הַבָּמוֹת״ וְגוֹ׳. וּבְרָכָה כַּעֲבוֹדָה הִיא שֶׁנֶּאֱמַר (דברים י ח) ״לְשָׁרְתוֹ וּלְבָרֵךְ בִּשְׁמוֹ״. וְכֵן כֹּהֵן שֶׁהֵמִיר לְעַכּוּ״ם אַף עַל פִּי שֶׁחָזַר בּוֹ אֵינוֹ נוֹשֵׂא אֶת כַּפָּיו לְעוֹלָם. וּשְׁאָר הָעֲבֵרוֹת אֵין מוֹנְעִין:
[Lack of] maturity: What is implied? A young priest should not recite the priestly blessings until he grows a full beard.
Intoxication: What is implied? A [priest] who drank a revi'it of wine at one time should not recite the priestly blessings until the effects of the wine wear off. [This restriction was imposed] because an association was established between [reciting the priestly] blessing and service [in the Temple].
Should [a priest] drink a revi'it of wine on two different occasions or mix a small amount of water in it, he is permitted [to recite the priestly blessings]. If he drank more than a revi'it, even though it was mixed with water or even though he drank it intermittently, he should not recite the priestly blessings until the effects of the wine wear off.
How much is a revi'it? [The volume of an area] two fingerbreadths by two fingerbreadths and two and seven tenths of a fingerbreadth high. Whenever the term "finger" is mentioned as a measure throughout the entire Torah, it refers to a thumbbreadth. The thumb is called bohen yad [in the Torah].
דהַשָּׁנִים כֵּיצַד. כֹּהֵן נַעַר לֹא יִשָּׂא אֶת כַּפָּיו עַד שֶׁיִּתְמַלֵּא זְקָנוֹ. וְהַיַּיִן כֵּיצַד. מִי שֶׁשָּׁתָה רְבִיעִית יַיִן בְּבַת אַחַת אֵינוֹ נוֹשֵׂא אֶת כַּפָּיו עַד שֶׁיָּסִיר אֶת יֵינוֹ מֵעָלָיו לְפִי שֶׁהֻקְּשָׁה בְּרָכָה לַעֲבוֹדָה. שָׁתָה רְבִיעִית יַיִן בִּשְׁתֵּי פְּעָמִים אוֹ שֶׁנָּתַן לְתוֹכוֹ מְעַט מַיִם מֻתָּר. וְאִם שָׁתָה יוֹתֵר מֵרְבִיעִית אַף עַל פִּי שֶׁהָיָה מָזוּג אַף עַל פִּי שֶׁשְּׁתָאוֹ בְּכַמָּה פְּעָמִים לֹא יִשָּׂא אֶת כַּפָּיו עַד שֶׁיָּסִיר אֶת יֵינוֹ מֵעָלָיו. וְכַמָּה הִיא רְבִיעִית אֶצְבָּעִים עַל אֶצְבָּעִים בְּרוּם אֶצְבָּעִים וַחֲצִי אֶצְבַּע וְחֹמֶשׁ אֶצְבַּע כְּגוּדָל. וְזֶה הָאֶצְבַּע שֶׁמּוֹשְׁחִין בּוֹ בְּכָל הַתּוֹרָה כֻּלָּהּ הוּא הַגּוּדָל וְהוּא הַנִּקְרָא בֹּהֶן יָד:
The ritual impurity of [the priest's] hands: What is implied? A priest who did not wash his hands should not recite the priestly blessing. Rather, he should wash his hands to the wrist, as is done when sanctifying the hands for the service in the Temple, as [Psalms 134:2] states: "Raise up your hands [in] holiness and bless God."
A challal does not recite the priestly blessing, for he is not a priest.
הטֻמְאַת הַיָּדַיִם כֵּיצַד. כֹּהֵן שֶׁלֹּא נָטַל אֶת יָדָיו לֹא יִשָּׂא אֶת כַּפָּיו אֶלָּא נוֹטֵל אֶת יָדָיו עַד הַפֶּרֶק כְּדֶרֶךְ שֶׁמְּקַדְּשִׁין לַעֲבוֹדָה וְאַחַר כָּךְ מְבָרֵךְ שֶׁנֶּאֱמַר (תהילים קלד ב) ״שְׂאוּ יְדֵכֶם קֹדֶשׁ וּבָרַכוּ אֶת יְיָ׳״. וְהֶחָלָל אֵינוֹ נוֹשֵׂא אֶת כַּפָּיו לְפִי שֶׁאֵינוֹ בְּכִהוּנוֹ:
Mishneh Torah (Moznaim)
Featuring a modern English translation and a commentary that presents a digest of the centuries of Torah scholarship which have been devoted to the study of the Mishneh Torah by Maimonides.
A priest who does not have any of the factors which hinder the recitation of the priestly blessings mentioned above should recite the priestly blessing, even though he is not a wise man or careful in his observance of the mitzvot. [This applies] even though the people spread unwholesome gossip about him, or his business dealings are not ethical.
He should not be prevented from [reciting the priestly blessings] because [reciting these blessings] is a positive mitzvah incumbent on each priest who is fit to recite them. We do not tell a wicked person: Increase your wickedness [by] failing to perform mitzvot.
וכֹּהֵן שֶׁלֹּא הָיָה לוֹ דָּבָר מִכָּל אֵלּוּ הַדְּבָרִים הַמּוֹנְעִין נְשִׂיאַת כַּפַּיִם אַף עַל פִּי שֶׁאֵינוֹ חָכָם וְאֵינוֹ מְדַקְדֵּק בְּמִצְוֹת אוֹ שֶׁהָיוּ הַבְּרִיּוֹת מְרַנְּנִים אַחֲרָיו אוֹ שֶׁלֹּא הָיָה מַשָּׂאוֹ וּמַתָּנוֹ בְּצֶדֶק הֲרֵי זֶה נוֹשֵׂא אֶת כַּפָּיו וְאֵין מוֹנְעִין אוֹתוֹ לְפִי שֶׁזּוֹ מִצְוַת עֲשֵׂה עַל כָּל כֹּהֵן וְכֹהֵן שֶׁרָאוּי לִנְשִׂיאַת כַּפַּיִם וְאֵין אוֹמְרִים לְאָדָם רָשָׁע הוֹסֵף רֶשַׁע וְהִמָּנַע מִן הַמִּצְוֹת:
Do not wonder: "What good will come from the blessing of this simple person?" for the reception of the blessings is not dependent on the priests, but on the Holy One, blessed be He, as [Numbers 6:27] states: "And they shall set My name upon the children of Israel, and I shall bless them." The priests perform the mitzvah with which they were commanded, and God, in His mercies, will bless Israel as He desires.
זוְאַל תִּתְמַהּ וְתֹאמַר וּמַה תּוֹעִיל בִּרְכַּת הֶדְיוֹט זֶה. שֶׁאֵין קִבּוּל הַבְּרָכָה תָּלוּי בַּכֹּהֲנִים אֶלָּא בְּהַקָּדוֹשׁ בָּרוּךְ הוּא שֶׁנֶּאֱמַר (במדבר ו כז) ״וְשָׂמוּ אֶת שְׁמִי עַל בְּנֵי יִשְׂרָאֵל וַאֲנִי אֲבָרַכֶם״. הַכֹּהֲנִים עוֹשִׂים מִצְוָתָן שֶׁנִּצְטַוּוּ בָּהּ וְהַקָּדוֹשׁ בָּרוּךְ הוּא בְרַחֲמָיו מְבָרֵךְ אֶת יִשְׂרָאֵל כְּחֶפְצוֹ:
The people standing behind the priests are not included in the blessing. Those standing at their sides are included in the blessing. [Even] if there is a partition - even an iron wall - between the priests and the people who are being blessed, since they are facing the priests, they are included in the blessing.
חעַם שֶׁהֵם אֲחוֹרֵי הַכֹּהֲנִים אֵינָם בִּכְלַל הַבְּרָכָה. וְהָעוֹמְדִים מִצִּדֵּיהֶן הֲרֵי הֵם בִּכְלַל הַבְּרָכָה. וְאִם הָיְתָה מְחִצָּה בֵּין הַכֹּהֲנִים וּבֵין הַמִּתְבָּרְכִים אֲפִלּוּ הִיא חוֹמָה שֶׁל בַּרְזֶל הוֹאִיל וּפְנֵיהֶם מוּל פְּנֵי הַכֹּהֲנִים הֲרֵי הֵם בִּכְלַל הַבְּרָכָה:
The priestly blessing is recited [only] when ten people [are present]. The priests can be included in that number.
If [the congregation in a particular] synagogue are all priests, they should all recite the priestly blessing. Who should they bless? Their brethren in the north and the south. Who will respond "Amen" to their [blessings]? The women and the children. If more than ten priests remain besides those who ascend to the duchan, these ten [priests] respond "Amen" and the remainder of the priests recite the blessings.
טנְשִׂיאַת כַּפַּיִם בַּעֲשָׂרָה וְכֹהֲנִים מִן הַמִּנְיָן. בֵּית הַכְּנֶסֶת שֶׁכֻּלָּן כֹּהֲנִים כֻּלָּם נוֹשְׂאִים אֶת כַּפֵּיהֶם. וּלְמִי הֵם מְבָרְכִים לְאַחֵיהֶם שֶׁבַּצָּפוֹן וְלַאֲחֵיהֶם שֶׁבַּדָּרוֹם. וּמִי עוֹנֶה אַחֲרֵיהֶם אָמֵן הַנָּשִׁים וְהַטַּף. וְאִם נִשְׁאֲרוּ שָׁם עֲשָׂרָה כֹּהֲנִים יוֹתֵר עַל אֵלּוּ שֶׁעָלוּ לַדּוּכָן הָעֲשָׂרָה עוֹנִין אָמֵן וְהַשְּׁאָר מְבָרְכִין:
When there is no priest in the community other than the leader of the congregation, he should not recite the priestly blessings. If he is sure that he can recite the priestly blessings and return to his prayers [without becoming confused], he may [recite the priestly blessing].
If there are no priests present at all, when the leader of the congregation reaches [the blessing] Sim shalom, he recites [the following prayer]:
Our God and God of our fathers, bless us with the threefold blessing written in the Torah by Moses, Your servant, and recited by Aharon and his sons, the priests, Your consecrated people, as it is said:
May God bless you and keep you.
May God shine His countenance upon you and be gracious to you.
May God turn His countenance to you and grant you peace.
And they shall set My name upon the children of Israel and I will bless them.
The people do not respond "Amen" to these blessings. He [resumes his recitation of the Shemoneh Esreh], beginning the recitation of [the blessing] Sim shalom.
יצִבּוּר שֶׁלֹּא הָיָה בָּהֶן כֹּהֵן אֶלָּא שְׁלִיחַ צִבּוּר לְבַדּוֹ לֹא יִשָּׂא אֶת כַּפָּיו. וְאִם הָיְתָה הַבְטָחָתוֹ שֶׁהוּא נוֹשֵׂא אֶת כַּפָּיו וְחוֹזֵר לִתְפִלָּתוֹ רַשַּׁאי. וְאִם אֵין לָהֶם כֹּהֵן כְּלָל כְּשֶׁיַּגִּיעַ שְׁלִיחַ צִבּוּר לְשִׂים שָׁלוֹם אוֹמֵר אֱלֹהֵינוּ וֵאלֹהֵי אֲבוֹתֵינוּ בָּרְכֵנוּ בַּבְּרָכָה הַמְשֻׁלֶּשֶׁת בַּתּוֹרָה הַכְּתוּבָה עַל יְדֵי משֶׁה עַבְדְּךָ הָאֲמוּרָה מִפִּי אַהֲרֹן וּבָנָיו כֹּהֲנִים עַם קְדוֹשֶׁךָ כָּאָמוּר (במדבר ו כד) ״יְבָרֶכְךָ יְיָ׳ וְיִשְׁמְרֶךָ״ (במדבר ו כה) ״יָאֵר יְיָ׳ פָּנָיו אֵלֶיךָ וִיחֻנֶּךָּ״ (במדבר ו כו) ״יִשָּׂא יְיָ׳ פָּנָיו אֵלֶיךָ וְיָשֵׂם לְךָ שָׁלוֹם״ (במדבר ו כז) ״וְשָׂמוּ אֶת שְׁמִי עַל בְּנֵי יִשְׂרָאֵל וַאֲנִי אֲבָרַכֶם״. וְאֵין הָעָם עוֹנִין אָמֵן. וּמַתְחִיל וְאוֹמֵר שִׂים שָׁלוֹם:
A priest who recited the priestly blessings and went to another synagogue and found the congregation in the midst of prayer, before the [recitation of] the priestly blessings, should bless them. [He may recite the priestly blessings] several times during the day.
A priest who does not move from his place to ascend to the duchan when the leader of the congregation recites [the blessing] R'tzey should not ascend [to the duchan] during that prayer service. However, if he moved [from his place], even though he did not reach the duchan until after the [conclusion of the blessing R'tzey], he may ascend [the duchan] and bless [the people].
יאכֹּהֵן שֶׁנָּשָׂא אֶת כַּפָּיו בְּבֵית הַכְּנֶסֶת וְהָלַךְ לְבֵית הַכְּנֶסֶת אַחֵר וּמָצָא צִבּוּר שֶׁמִּתְפַּלְּלִין וְלֹא הִגִּיעוּ לְבִרְכַּת כֹּהֲנִים נוֹשֵׂא יָדָיו לָהֶן וּמְבָרְכָן. וַאֲפִלּוּ כַּמָּה פְּעָמִים בְּיוֹם. כֹּהֵן שֶׁלֹּא עָקַר רַגְלָיו מִמְּקוֹמוֹ לַעֲלוֹת לַדּוּכָן בְּשָׁעָה שֶׁאָמַר שְׁלִיחַ צִבּוּר רְצֵה שׁוּב אֵינוֹ עוֹלֶה בְּאוֹתָהּ תְּפִלָּה. אֲבָל אִם עָקַר רַגְלָיו לַעֲלוֹת אַף עַל פִּי שֶׁלֹּא הִגִּיעַ לַדּוּכָן אֶלָּא אַחַר עֲבוֹדָה הֲרֵי זֶה עוֹלֶה וּמְבָרֵךְ:
Any priest who does not ascend to the duchan - even though he neglects [the performance] of [only] one commandment - is considered as if he violated three positive commandments, as [Numbers 6:23-27] states: "This is how you shall bless the children of Israel," "Say to them," "And you shall set My name..."
Any priest who does not recite the priestly blessing will not be blessed, and any priest who blesses [the people] will be blessed, as [Genesis 12:3] states: "And I will bless those who bless you."
יבכָּל כֹּהֵן שֶׁאֵינוֹ עוֹלֶה לַדּוּכָן אַף עַל פִּי שֶׁבִּטֵּל מִצְוַת עֲשֵׂה אַחַת הֲרֵי זֶה כְּעוֹבֵר עַל שָׁלֹשׁ עֲשֵׂה שֶׁנֶּאֱמַר (במדבר ו כג) ״כֹּה תְבָרַכוּ אֶת בְּנֵי יִשְׂרָאֵל״ (במדבר ו כג) ״אָמוֹר לָהֶם״ (במדבר ו כז) ״וְשָׂמוּ אֶת שְׁמִי״. וְכָל כֹּהֵן שֶׁאֵינוֹ מְבָרֵךְ אֵינוֹ מִתְבָּרֵךְ וְכָל כֹּהֵן הַמְבָרֵךְ מִתְבָּרֵךְ שֶׁנֶּאֱמַר (בראשית יב ג) ״וַאֲבָרַכָה מְבָרְכֶיךָ״:
סְלִיקוּ הִלְכוֹת תְּפִלָה בְּסִיַּעְתָּא דִּשְׁמַיָּא