Justin Martyr, on Exod 17:12

“And Moses’ hands were heavy: so they took a stone, and put under him, and he sat on it: and Aaron and Hur stayed up his hands on both sides. And it came to pass that his hands were not weary until sunset.”

“For it was not because Moses so prayed that the people were stronger, but because, while one who bore the name of Jesus (Joshua) was in the forefront of the battle, he himself made the sign of the cross. For who of you knows not that the prayer of one who accompanies it with lamentation and tears, with the body prostrate, or with bended knees, propitiates God most of all? But in such a manner neither he nor any other one, while sitting on a stone, prayed. Nor even the stone symbolized Christ, as I have shown.”

Imported from an open dataset — not yet checked against the printed edition.