Dear Rabbi, I have several questions concerning blessings 1. Can a Cohen give a priestly blessing to another Cohen (for example if he is ill)? 2.What should a Cohen do during tefila in shul if he would prefer not duchan (if he does not feel he is able to because he has a grudge against another person in shul or if he feels physically unable because of a passing illness (flu-like) and it seems hard for him to ascent)). Should he then leave the shul (the room of the shul)? Would it be ok if he stayed during the Birkat HaCohanim? (even though he himself is a Cohen) 3. Does the verse where God says to Abraham "And I will bless them that bless thee, and him that curseth thee will I curse" also apply to Jews, meaning that hypothetically to a Jew who would curse the Jewish people, or the opposite, a Jews who blesses the Jewish people? Can a Cohen duchaning (or a non-Cohen expressing his blessing) also be seen in that sense (of Genesis, 12,3) 4. Can basically every Jew give a blessing (being done in an approprate way) to every Jew? 5. Can a Jew also give a blessing to a non-Jew? If the Jew is a Cohen, is it still allowed? Would he be allowed to use the priestly blessing? Thank you very much !!!

I will try to focus on some of the questions of the cohen's blessing . You asked many things each of which has many details. The underlying principle behind the cohen's blessing is that G-d wishes to bless his people daily and he chose the cohanim to be his agents for this blessing since they are the ones designated to serve G-d in the Bet Hamikdash and all their thought are involved with the service of Hashem. The cohen's blessing is a unique blessing and is carried out in the Bet Knesset when there is a minyan. It is not just wishing another person well, which one may do to whom he sees fit. There is nothing limiting a cohen from carrying out his blessing if he is not well. It is not like since the cohen is carrying a virus that he transfers his virus to the others in the Bet Knesset. However, if a cohen is not well with fever or the like, normally a person in such a condition would not come to the Bet Knesset and therefore he will not be blessing anybody while at home. Nevertheless, if the cohen is in the Bet Knesset and does not feel well enough for duchaning, he should leave the Bet Knesset for the duration of the duchaning. Shulchan Aruch (Orach Cham 128:4) However, a cohen with certain physical blemishes does not carry out the cohen's blessing as specified in the Shulchan Aruch (Orach Cham 128.) A cohen who bears a grudge against the community should not duchan, since his blessing must stem from love. The Zohar views a cohen who is hated or he hates the community very severely and therefore the cohen must not be in the Bet Knesset or he must remove his hate from his heart before the blessing. (Mishna Brura 128:37). Some say that this rule applies even if the cohen hates a single individual.(Shut Si'ach Yitzchak 78). One Jew may bless another Jew, even if saying the "birkat Cohanim" the same way a person blesses his children with the "birkat Cohanim". A Jew may bless and pray for a gentile. (Yechaveh Da'at 6:60) Have a happy Purim.