horn of salvation - that is “strength of salvation,” or “mighty Salvation,” meaning the Savior Himself, whom Simeon calls “Thy Salvation” (Luk 2:30). The metaphor is taken from those animals whose strength is in their horns (Psa 18:2; Psa 75:10; Psa 132:17).
house of ... David - This shows that Mary must have been known to be of the royal line, independent of Joseph; of whom Zacharias, if he knew anything, could not know that after this he would recognize Mary.