“The Blessing” is a Christian song based on the words that God said to Moses about the words that Aaron and his sons were to give to the people of Israel to bless them.
These words are in Numbers 6:24-27:
The Lord bless thee, and keep thee: The Lord make his face shine upon thee, and be gracious unto thee: The Lord lift up his countenance upon thee, and give thee peace. And they shall put my name upon the children of Israel, and I will bless them.