Say to Aaron and his sons: Thus shall you bless the children of Israel, and you shall say to them:
Rashi
אמור is infinitive. Similar forms are זכור (Exodus 20:8), שמור (Deuteronomy 5:12); in O. F. disant, (English = saying).
אמור להם SAYING UNTO THEM — so that all of them should hear the blessing (it would not suffice to pronounce the blessings upon the Israelites in their absence; cf. Sifrei Bamidbar 39).
אמור is written plene (with ו after the מ) thus indicating: ye shall not bless them hurriedly and hastily, but devoutly and with a whole heart (Midrash Tanchuma, Nasso 10).
Hebrew and Aramaic words are the commentator’s citations of the sacred text; the English translation that follows each is the translator’s.
Imported from an open dataset — not yet checked against the printed edition.