“Open my eyes and I will gaze at wonders from Your Torah.”1גַּל עֵינַי וְאַבִּיטָה נִפְלָאוֹת מִתּוֹרָתֶךָ,
The Rebbe Maharash writes in his maamar2 that focuses on this verseוְכָתַב אַדְמוּ"ר מַהֲרָ"שׁ בְּמַאֲמָרוֹ עַל פָּסוּק זֶה,
that based on what is stated in the Alter Rebbe’s Siddur im Dach, Shaar Lag BaOmer3דְּעַל-פִּי מַה שֶּׁכָּתוּב בַּ'סִידוּר' שַׁעַר הַלַ"ג בָּעוֹמֶר
that the allusion to Lag BaOmer in the Torah is in the verse4 “This mound is witness...,” for the word גל “mound,” transposes the letters ל"ג, Lag,שֶׁהָרֶמֶז בַּתּוֹרָה עַל לַ"ג בָּעוֹמֶר הוּא בַּפָּסוּק עֵד הַגַּל הַזֶּה,
the verse “Open my eyes” can also be explained as referring to Lag BaOmer, for it also uses the word גל.גַּם הַפָּסוּק גַּל עֵינַי יִתְבָּאֵר עַל לַ"ג בָּעוֹמֶר.
Based on the well-known concept that all the teachings of the Torah are meticulously precise,וְעַל-פִּי הַיָּדוּעַ שֶׁכָּל הָעִנְיָנִים שֶׁבַּתּוֹרָה הֵם בְּתַכְלִית הַדִּיּוּק,
it is possible to say that the fact that the allusion to Lag BaOmer in the verse “Open my eyes”יֵשׁ לוֹמַר, דְּזֶה שֶׁהָעִנְיָן דְּלַ"ג בָּעוֹמֶר שֶׁבַּפָּסוּק גַּל עֵינַי גוֹ'
is derived from the allusion to Lag BaOmer in the verse “This mound is witness...”לְמֵדִין מֵהָעִנְיָן דְּלַ"ג בָּעוֹמֶר שֶׁבַּפָּסוּק 'עֵד הַגַּל הַזֶּה'
teaches that to reach the revelation of G‑dliness alluded to by the verse “Open my eyes…”הוּא, כִּי בִּכְדֵי לָבֹא לְעִנְיַן גַּל עֵינַי גוֹ'
it is necessary that, as a preface, there take place the process of separation, alluded to by “This mound is witness....”הוּא עַל-יְדֵי 'עֵד הַגַּל הַזֶּה'.
As will be explained in sec. 9, the correlation of the two verses is not merely a coincidence of them both containing the word לג. Instead, the concept derived from the verse “Open my eyes” has its source and depends on the concept derived from the verse “This mound is witness.”

Summary

Based on the Alter Rebbe’s statement that the verse “This mound is witness...” is an allusion to Lag BaOmer, the Rebbe Maharash states that the verse, “Open my eyes and I will gaze at wonders from Your Torah,” alludes to Lag BaOmer. To reach the revelation of G‑dliness alluded to by “Open my eyes” it is necessary that, as a preface, there take place the process of separation, alluded to by “This mound is witness....”