Zacharias said to the angel, "How can I be sure of this? For I am an old man, and my wife is well advanced in years."
Gabriel (lit. man of God) had appeared twice to Daniel to give him information and understanding (Daniel 8:16; Daniel 9:21). He did the same for Zechariah here (cf. Luke 1:67-79). Gabriel could have been harder on Zechariah than he was, but he was not probably because Zechariah believed and only wanted confirmation (cf. Judges 6:36-40; Judges 13:2-21). He was not asking for a sign so he could believe.