כָּל הַחֹדֶשׁ אֵין אוֹמְרִים תַּחֲנוּן. אַחַר אֲמִירַת הַנָּשִׂיא אוֹמְרִים יְהִי רָצוֹן הַנִּדְפָּס בְּסִדּוּר תּוֹרָה אוֹר, וְגַם כֹּהֲנִים וּלְוִיִּם אוֹמְרִים אוֹתוֹ.

Tachanun1 is omitted throughout this month.

After reciting the [passages recounting the offerings] of the Nesi’im,2 we add the prayer beginning Yehi ratzon, as printed in the Siddur Torah Or. Kohanim and levi’im should also recite it.3

אַאַמוּ"ר צִיוָּה לְגִיסוֹ הָרַב מֹשֶׁה האָרעֶנְשׁטֵיין הַכֹּהֵן לֵאמֹר הַיְּהִי רָצוֹן שֶׁאַחַר הַנָּשִׂיא, וְאָמַר לוֹ כִּי אֲפִילוּ כֹּהֵן וְלֵוִי צָרִיךְ לְאָמְרוֹ, כִּי זֶה שַׁיָּךְ לָעִבּוּר.

My revered father, the Rebbe [Rashab], instructed his brother-in-law, R. Moshe Hornstein HaKohen to recite the Yehi ratzon after the offering of each of the Nesi’im. He told him that even a kohen and a levi should recite this prayer, because [souls are sometimes] impregnated [by other souls].

To Fill In the Background

The Kabbalistic metaphor employed here is ibur (“pregnancy”), for just as a mother carries a child, so one soul sometimes carries another soul. These two souls share a symbiotic relationship. On the one hand, when a person presently studies Torah and observes mitzvos, he can elevate and complement the Divine service performed by the impregnated soul in its previous lifetime. Conversely, that impregnated soul now adds vitality to its present, host soul, making it a sensitive receptor to spiritual influences that it could not have perceived alone.

In the situation at hand, a kohen or a levi can be impregnated by the soul of a person from another Tribe, and that soul will uplift and inspire him in ways that he could not attain himself.