“The ETERNAL spoke to Moses: Speak to Aaron and his sons: Thus shall you bless the people of Israel. Say to them...” (Num. 6:22-23)
This is how it works, in the way that the Baal Shem Tov used to rebuke people with the verse “The ETERNAL is your shadow” (Ps. 121:5), which is to say: Just as the shadow does precisely what a person does, so does the Blessed Creator (as it were) do just as we do. Therefore, we have to do mitzvot and give tzedakah and have compassion on the poor in order that the Blessed Creator will express goodness toward us as well.
Now, this fact is called “thus (ko)” – since the meaning of “ko” is “thus,” that is, just as one does, so too does the Blessed Creator do as well.
It is well known that the Blessed Creator desires to do good for the people Israel, and that even more than the calf desires to suck, the cow wants to suckle (B. Pesachim 112a). Therefore, when we stand to pray before the Blessed Creator, reciting the Shmoneh Esrei or any other prayers of supplication, we have to be careful only to pray so that the Blessed Creator will derive delight from our prayers. This is similar to the mishnah (M. Avot 2:8): “If you have learned a great deal of Torah, don’t hold it as a positive thing for yourself, since it was for this purpose that you were created.” That is, everything we do should only be for the sake of delighting the Creator.
It is also well known that when we pray only for ourselves, we are in the posture of a recipient. When we want to receive something, we hold out our hands with the backs downward and the palms upward. But, when we pray only so that the Blessed Creator will have delight from our prayers, we are in the posture of a provider, since (as it were) we are providing delight for the Blessed Creator – and one who provides for another holds his hands with the backs upward and the palms downward.
Now, the Priestly Blessing is recited with hands raised, that is, with the backs upward and the palms down, toward their faces, just like one who is in the position of providing for another. This, then, helps to interpret the verse, “Thus (ko) shall you bless the people of Israel”: you shall bless the people of Israel so that the Blessed Creator will have delight from your act. In this way, you will (as it were) be one of those who give to the Blessed Creator, following which the Blessed Creator will provide every good thing and blessing for Israel. This is what we taught above regarding the term “ko” – just as Israel does, so too does the Blessed Creator (as it were), providing all good things and blessings, life and peace. Amen.