B'ahavah

Someone in my brother's shiur asked him why do the Kohanim say livareich es amo Yisroel beahavah. He answered that Rabbeinu Bachye writes that we say liyachedcha beahavah and ahavah means Shechinah. We can suggest that the Shechinah rested on the fingers of the Kohanim when they duchaned, so it is for this reason that they recite the word beahavah.

I found several answers to this question:

1. Some say that "b'ahavah" is based upon the Chazal that that birchas Kohanim should be said slowly and with kavanah.

2. M"B paskens based upon M"A and Zohar that if a Kohen hates someone or someone hates him, he cannot duchen.

3. Reb yerucham Fishel explains it based upon the halacha that birchas Kohanim must be recited "panim k'neged panim" (face to face), and that is a sign of love, as we find by the keruvim.

4. Based upon the Kedushas Levi who explains the halacha that the Kohanim must have their palms down during birchas Kohanim. This is because they are displaying that they are givers and not takers. Accordingly, that is why they say "b'ahavah" to show that they are giving out of love, and they want nothing in return (perhaps not even a "yasherko'ach, like the Reshash says).