Psalms 80:15

“And the vineyard ... - Gesenius renders this as a verb: “Protect;” that is, “Protect or defend what thy right hand hath planted.” So the Septuagint renders it κατάρτισαι katartisai - and the Vulgate, perfice, fit, prepare, order. Prof. Alexander renders it sustain. DeWette, “Guard what thy right hand hath planted.” This is doubtless the true idea. It is a prayer that God would guard, sustain, defend what he had planted; to wit, the vine which he had brought out of Egypt, Psalms 80:8. And the branch - literally, the son; that is, the offspring or shoots of the vine. Not merely the original plant - the parent stock - but all the branches which had sprung from it and which had spread…”

“80:15 Israel was the son that God had brought out of Egypt (see Hos 11:1) and planted in the Holy Land.”

“vineyard: Psa 80:8; Isa 5:1, Isa 5:2; Jer 2:21; Mar 12:1; Joh 15:1 the branch: Or, "the Son," ben, or as 18 manuscripts, LXX, Vulgate, Syriac, Arabic, and Ethiopic read, ben adam, "Son of man;" which the Targumist renders makla mesheecha, "the King Messiah." Psa 89:21; Isa 11:1, Isa 49:5; Jer 23:5, Jer 23:6; Eze 17:22-24; Zac 3:8, Zac 6:12 Psalms 80:16”