The Gospel of Luke states that while Zechariah ministered at the altar of incense, an angel of the Lord appeared and announced to him that his wife would give birth to a son, whom he was to name John, and that this son would be the forerunner of the Lord (Luke 1:12–17)
 Citing their advanced age, Zechariah asked with disbelief for a sign whereby he would know the truth of this prophecy. In reply, the angel identified himself as Gabriel, sent especially by God to make this announcement, and added that because of Zechariah's doubt he would be struck dumb and "not able to speak, until the day that these things shall be performed".