Luke 1:68

Blessed be the Lord, the God of Israel; For he hath visited and wrought redemption for his people. And hath raised up a horn of salvation for us in the house of his servant David.

Here Zacharias was speaking, not of his own son John, but of Jesus the Christ. The use of the past tense, at a time when Jesus had not yet been born, is prophetic, a tense peculiar to the Holy Scriptures, in which future events are announced in the past tense, implying the certainty of fulfillment. What God promises is as certain as if it had already happened.

Horn of salvation ... This metaphor was one which, to the Israelites, suggested the very greatest strength. Such men as Abraham and Moses were said to be "horns" of Israel.[35]

In the house of his servant David ... This, like the words of the angel (Luke 1:32), shows that Mary was a descendent of David.