Pseudo-Barnabas

Learn fully then, children of love, concerning all things, for Abraham, who first circumcised, did so looking forward in the spirit to Jesus and had received the doctrines of the three letters. For it says, “Abraham circumcised from his household eighteen men and three hundred.” What then was the knowledge that was given to him? Notice that he first mentions the eighteen, and after a pause the three hundred. The eighteen is I (= 10) and H (= 8)—you have Jesus—and because the cross was destined to have grace in the T he says “and three hundred.” So he indicates Jesus in the two letters and the cross in the other. He knows this who placed the gift of his teaching in our hearts.