Albert Barnes Commentary Psalms 132:17

"There will I make the horn of David to bud: I have ordained a lamp for mine anointed." — Psalms 132:17 (ASV)

There will I make your horn of David to bud - The horn was an emblem of power, and then of success or prosperity. See the notes at Luke 1:69. The word rendered “to bud” means to grow, or to shoot forth like a plant, or as grass grows; it can then be applied to anything that shoots forth or grows. The allusion here would seem to be to a horn as it shoots forth on the head of an animal.

So David would be endowed with growing strength; he would have the means of defending himself against his enemies and of securing victory. The language had no original reference to the Messiah, but it is not improperly applied to him (as springing from David) in Luke 1:69. On the word horn, see the notes at Psalm 75:4. Compare Psalm 89:17, Psalms 89:24; Psalms 92:10; Psalms 112:9; Daniel 7:8; Daniel 8:5.

I have ordained a lamp for my anointed - Margin, a candle. I have appointed; that is, I have given him that which will always be like a lamp or guide to him, by which he will see to walk. I have given him true and precious promises, which will be to him as a lamp, a candle, or a lantern is to one walking in the night. See Psalm 18:28, note; Psalms 119:105, note.