Targum Pseudo-Jonathan on (Genesis 12:3) performs one of its most characteristic moves — it drops the future straight into the past. The plain verse says, I will bless those who bless you. The Targum names names.
The blessings will flow through the priests, says the Targumist, who will spread forth their hands in prayer and bless thy sons. Every time you read this verse, the Aramaic expects you to see the birkat kohanim — the priestly blessing of (Numbers 6:24-26) — raising the descendants of Abram under the outstretched fingers of his eventual kinsmen. The covenant already contains the Temple. The promise already contains the liturgy.
And the curse? The Targumist names the curser too. It is Balaam, the foreign prophet who in (Numbers 22-24) will be hired by Balak to curse Israel and will find his mouth helpless to do anything but bless. Balaam who will curse them, I will curse — and they shall slay him with the mouth of the sword. The Targum remembers how that story ends. Balaam dies by Israelite blade in (Numbers 31:8), and the promise to Abram is fulfilled in the smallest, sharpest sentence.
The Targumist is doing theology through biography. The abstract promise of blessing and curse is not an insurance clause; it is a pair of real men. One set of hands that will lift the Torah. One set of lips that will try to use language as a weapon. The Holy One has already sorted them in His ledger — and the ledger, in the Targum, is never empty.