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 themselves over the land.
That thou madest strong for thyself - Thou didst cause it to grow so vigorously for thine own use or honor. On that account, we now call on thee to defend what is thine own.