This blessing is known in Hebrew as the "Nesiat Kapayim" and is performed in Jewish synagogues by the Kohanim. These are priests who are direct descendants of Aaron (the older brother of Moses).
The text is a quotation from Numbers Chapter 6:-
The LORD bless you
and keep you;
the LORD make his face shine upon you
and be gracious to you;
the LORD turn his face toward you
and give you peace.
(Numbers 6:24-26, NIV Bible)
In 1970, archelogists uncovered a silver amulet with this blessing etched upon it. The find is thought to date back to the seventh century B.C., making this the oldest known remanant of scripture.