The Martyrdom of Zacharias

Circa 1315-21
Mosaic
Church of the Holy Saviour in Chora, Istanbul

This mosaic is a very literal rendering of ¶¶22b-23 of The Protevangelium of James. In the background, beyond the first line of hills, "Elizabeth, having heard that they were searching for John [i.e. the baby John the Baptist], took him and went up into the hill-country, and kept looking to conceal him. And Elizabeth, groaning with a loud voice, says: O mountain of God, receive mother and child." The door-like opening below represents the mountain's response: "immediately the mountain was cleft, and received her." The now-obscured light-colored area above pictures the next sentence in the narrative: "And a light shone about them, for an angel of the Lord was with them, watching over them." The soldier pursuing Elizabeth with drawn sword is not in the Protevangelium but is prescribed in the Byzantine Guide to Pictures (Didron II, 901).

The scenes in the foreground represent ¶ 23:

And Herod searched for John, and sent officers to Zacharias, saying: Where hast thou hid thy son? And he, answering, said to them: I am the servant of God in holy things, and I sit constantly in the temple of the Lord: I do not know where my son is. And the officers went away, and reported all these things to Herod. And Herod was enraged, and said: His son is destined to be king over Israel. And he sent to him again, saying: Tell the truth; where is thy son? for thou knowest that thy life is in my hand. And Zacharias said: I am God's martyr, if thou sheddest my blood; for the Lord will receive my spirit, because thou sheddest innocent blood at the vestibule of the temple of the Lord. And Zacharias was murdered about daybreak.
In the Koran Zacharias is a prophet and the protector of Mary, which may explain why someone chose to obliterate his face but not the others.

Read more about images of the Slaughter of the Innocents
Read more about images of John the Baptist.

Source: this page at Wikimedia Commons.