Rabbi Levi explained the words "after these words" in to mean after Ishmael's words to Isaac. Ishmael told Isaac that Ishmael was more virtuous than Isaac in good deeds, for Isaac was circumcised at eight days (and so could not prevent it), but Ishmael was circumcised at 13 years. Isaac questioned whether Ishamel would incense Isaac on account of one limb. Isaac vowed that if God were to ask Isaac to sacrifice himself before God, Isaac would obey. Immediately thereafter (in the words of ) "God did prove Abraham."