"... The ancient and medieval commentators did not understand Abraham’s laughter in this manner. Already the Book of Jubilees, whose fifteenth chapter is an almost verbatim paraphrase of Genesis 17, states, “And Abraham fell on his face and rejoiced” (Jubilees 15:17), an interpretation shared by the Septuagint. The ancient Aramaic Targumim follow a similar path. Thus, for example, Onkelos: (And Abraham fell on his face and rejoiced), followed by Rashi. Similarly, Rav Sa’adya Gaon (va-yismaḥ), Kimhi (samaḥ be-libo), and Nahmanides. The identification of Abraham’s laughter as an expression of joy dictates in turn their explanations further along in the chapter. Thus, regarding Abraham’s question, “Shall a child be born to a man who is a hundred years old?,” Rashi writes: “There are expressions of astonishment that are fulfilled [i.e., rhetorically] ... So was this one [as if it had been] fulfilled. Thus he said in his heart, ‘Shall this kindness be done after all that the Holy One, blessed be he, has done for me?’ ” Abraham, according to Rashi, is self-effacing: “‘Would that Ishmael would live before you’ - I am not worthy to receive such a reward ..."