Bamidbar: 6:23 – Speak to Aaron and his sons, saying: Thus shall you shall bless the children of Israel, saying to them:
Ketubos 24b: A non-Cohen who “lifts up his hands” [to do the priestly blessing] transgresses a positive commandment as it says “thus shall you bless…” – You but not a non-Cohen; A prohibition that comes due to a positive command is a “positive prohibition”.
Torah Temimah Colloquial Translation on Note #131:
The issue of a stranger [non-Cohen] ”lifting his hands” is that when a Cohen goes up to ‘duchan’ [raised platform]to bless Israel with the blessing of the Cohanim. That is why when we often refer to the blessing of the Cohanim we use the phrase “lifting the hands” This, thereby, distinguishes it from the general blessings that certainly one cannot say are solely allowed to the Cohanim. Every person is permitted to bless and give blessings to his neighbor. Even a non-Cohen can give blessings. The essential unique aspect of the Priestly Blessing is in this aspect of “lifting hands” as we will examine shortly.
It is appropriate to investigate the common practice that we see of people blessing each other by placing their hands on the head of the person they are blessing, as we see is the general custom in weddings, etc. How can this be the custom given what we just explained that this is something set aside only for the Cohanim? Also, as noted above, a non-Cohen doing this would transgress a implied prohibition [there is no direct prohibition, rather it is an inferred prohibition by the fact that the Torah explicitly states that the Cohanim should bless the people.] It wouldn’t be plausible to say that the restriction of only having the Cohanim do this only applies in the Temple. I’ve never seen nor heard anyone propose that explanation and it would be an amazing proposal. Further, it would be implausible to say that the exclusivity of the Cohen for ‘lifting of hands’ only applies in a congregation of 10 men since it is a “holy service”. This is implausible because lifting of hands is only in the category of “alluded to” rather than a clear “law” as the RaN explains in Chapter 3 of Megillah.
Further, it appears to me that even for a Cohen, he is not permitted the bless this special blessing of “lifting the hands” in a time or place that is not set aside for this. The proof for this comes from the Gemora Megilla 27b where they ask Rabbi Eliezer ben Shamua what merit he had to enable him to live a long life. He replied, “I never did ‘lifting of hands’ without a blessing”. On the face of it, this story is hard to understand what great merit that would be for Rabbi Eliezer ben Shamua. Rather, one is forced to say that the explanation of the story is that Rabbi Eliezer ben Shamua never just did the ‘lifting of hands’ but rather only did it is the time that it was a mitzvah and when he was obligated to do it with a blessing.
Note also that in the Gemora Shabbos 118b it says as follows: “Rabbi Yossi says, ‘I never opposed the words of my friends [fellow rabbis]. I know about myself that I am not a Cohen but when my friends said to me to go up to the duchan I would go up.” Tosafot comments that Rabbi Yossi didn’t know what prohibition there would be involved in him [listening to his fellow rabbis to go up to the duchan] other than the [rabbinic prohibition] of making a needless blessing [that only the Cohanim are allowed to say for the ‘lifting of hands’. By the way, it was explained to this translator that perhaps Rabbi Yossi’s “friends”, the fellow rabbis, would have the authority to override something that was just a rabbinic prohibition.]Note that these few words of Tosafot have caused much rabbinic literature to be written amongst the Rishonim and Acharonim to attempt to explain these words of Tosafot. How can they say that the only prohibition would be on making a needless blessing? Isn’t a non-Cohen who does “lifting of hands” transgressing a “positive prohibition”? Also, the words of the Rabbi Yossi himself in the Gemora are extremely hard to understand. How could it be that he himself was not concerned about transgressing this prohibition of “lifting the hands” by a non-Cohen? In all the words of the commentators on this question, I have not found a satisfactory explanation.
[Therefore], I won’t restrain myself from explaining this in a new and amazing way that I saw in the introduction to the book by Rav Yerucham. He quotes this story of Rabbi Yossi but instead of the phrase “I know about myself that I am not a Cohen” amends the wording to be “I know about myself that I am not worthy”.
According to this way of reading the text when it says that his friends wanted him to go up to the raised platform, it was not to give the priestly blessing but rather to go up to the raised platform where the great sages would give speeches to the people. The duchan was a place that was high and stood out similar to an “itstabah”. As it says in the Gemora Baba Basra 21a: “they sat at the head of the “duchna”. Also the “Aruch” it notes that in the language of Ishmaelim, they call an “itztabah” a “duchan”. This is why in Gemora Megilla 3a and it other places it mentions the Leviim in their “duchans”.
If this is the case, then the issue with Rabbi Yossi was not about “lifting of hands” but rather about him [not wanting to go up, but ultimately listening to his friends to indeed] go up to the raised platform to give a speech to the people. The text of the Gemora merely needs amendation to “kedai” from “kohen”
Editor’s note: The Torah Temimah’s enthusiasm and excitement at not restraining himself from explaining the story of Rabbi Yossi in a new and amazing way is contagious.