18 And Zacharias said to the angel: According to what shall I know this? for I am old and my wife advanced in her days.
Luke 1:18 Cross References - Godbey
Luke 1:7
7 And there was no child to them, as Elizabeth was barren, and both were advanced in their days.
Luke 1:34
34 And Mary said to the angel; How shall this be, since I know not man?
Romans 4:19
19 and being not weak in faith, he considered not his body already dead, being about a hundred years old, and the deadness of Sarah's womb: