Behold, you will be silent and not able to speak, until the day that these things will happen, because you didn't believe my words, which will be fulfilled in their proper time."
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.