Surah 37. As-Saffat, Ayah 107

The epithet 'azim ("tremendous" or "mighty") renders it improbable that this sacrifice refers to nothing but the ram which Abraham subsequently found and slaughtered in Ishmael's stead (Genesis xxii, 13). To my mind, the sacrifice spoken of here is the one repeated every year by countless believers in connection with the pilgrimage to Mecca (al-hajj), which, in itself, commemorates the experience of Abraham and Ishmael and constitutes one of the "five pillars" of Islam. (See {22:27-37}, as well as {2:196-203}.)

 Allah sent a ram to be sacrificed in place of Ishmael.

The adjective qualifying "sacrifice" here, 'azim, (great, momentous) may be understood both in a literal and a figurative sense. In a literal sense it implies that a fine sheep or ram was substituted. The figurative sense is even more important. It was indeed a great and momentous occasion, when two men, with concerted will, "ranged themselves in the ranks" of those to whom self-sacrifice in the service of Allah was the supreme thing in life.