The blessing is performed by kohanim, male Jews with priestly heritage who have a clear patrilineal tradition leading back to Aaron the high priest, brother of Moses. The priestly blessing is said daily during the year as part of the morning prayer service, and twice during Sabbath and holiday morning prayer services. Before saying the blessing, men from the tribe of Levi wash the hands of the kohanim. The ritual may only be performed by a kohen and only in the presence of a quorum of ten Jews. A kohen who is under the influence of alcohol or in mourning may not perform the blessing.
The blessing is performed by the priests holding their hands up with the fingers spread in the manner made famous by Leonard Nimoy (a kohen) when he played Spock on the television series Star Trek. The fingers of both hands are separated so as to make five spaces between them; spaces are between the ring finger and middle finger of each hand, between the index finger and thumb of each hand, and the two thumbs touch each other at the knuckle. During the prayer, kohanim must cover their heads with their prayer shawls and hold up their hands towards the congregation of Israelites to make the blessing upon them.
May the LORD bless you and guard you,
May the LORD make His face shed light upon you and be gracious unto you,
May the LORD lift up His face unto you and give you peace.
The bi-annual priestly blessing is an impressive reminder of the glory of the Jewish people coming together as a nation to serve God, something that was entirely lacking until the Jews returned to Jerusalem 52 years ago.