Scenes from the life of Abraham. On the left, Sarah looks on as Abraham brings a calf to three angels, who bring a message from God that Sarah will have a child in her old age (Genesis 18). On the right, the divine hand extends from heaven to stop Abraham before he obediently sacrifices his son Isaac (Genesis 22). Detail of mosaic on the left wall of the presbytery, c.547. San Vitale Basilica, Ravenna, Italy.