In this Bible Blocks Christmas video we see that before the angel visited Mary, Gabriel proclaimed the birth of John the baptist to his father Zacharias who was burning incense in the temple. The angel says that Zacharias' wife Elizabeth will give birth in her old age and the child John will be filled with the Holy Spirit even in her womb. John would go before the Lord Jesus and make ready and prepare the people for His coming.

You can read this true story in a Bible: Luke 1:5-25