Mishneh Torah — Positive Mitzvot מצוות עשה, Chapter 26
The full Hebrew text of Mishneh Torah, Positive Mitzvot, Chapter 26, with English translation by Maimonides (Rambam).
לְבָרַךְ הַכּוֹהֲנִים אֶת יִשְׂרָאֵל, שֶׁנֶּאֱמָר: "כֹּה תְבָרְכוּ אֶת בְּנֵי יִשְׂרָאֵל" (במדבר ו, כג).
For the priests to bless the Jews, as [Numbers 6:23] states: "In this manner, you shall bless the children of Israel."