Rabbi Yehudah says it is because Hashem said to Avraham, " 'Koh,' Thus shall be your progeny," they merited the blessing which begins with "koh," Bircas Kohanim. Rabbi Nechemiah says the blessing is due to Yitzhak's merit which is based on the verse, "I and the youth shall go up till "koh" here." A last opinion states that the credit belongs to Yaakov for the verse says, " 'Koh,' thus shall you say to the house of Yaakov." All of these opinions are Torah true and credit is certainly owing to all three Avos. Bircas Kohanim is called a three pronged blessing (be'rachah ha' me' shu- leshes baTorah) because it is attributed to the Avos.

All of the Avos are alluded to in the language of the blessing. The names Avraham and Yitzhak contain 9 letters and Yaakov, who is referred to by the names Yaakov, Yeshurun, and Yisroel, contain 16 letters (Yaakov and Yeshurun are written "malei" or with vavim). The sum of the letters of the Avos equals 25 letters and through the merit of the Avos whose names contain 25 ("koh or "kaf hey") letters, Israel is blessed by Hashem. On Yom Kippur, the Jewish people are blessed three times with this tri-pronged blessing, during shacharis, musaf and ne'ilah due to the merits of their three Avos.

Bircas Kohanim is referred to as "nesias kapayim" or the raising of hands because the blessing contains 15 words which represent the 15 parts of a person's hand (the 14 parts of one's fingers and the palm itself). The word "koh" which precedes the blessing is made of two letters, 'kaf and hey." It is the "kaf" or hand that blesses with "hey" five fingers. The blessing, which is 15 words, is given by the kohein who raises 15 parts of his hand. Furthermore, since the blessing is given in three stages, the 15 is considered 45 words and this is indicated by the latter part of the verse which states "say to them," or "lahem," which is broken up as "lamed" or to "hey, mem" which equals 45.