Tendai posted:

Muslims believe that Islam (and Muhammad) descend from Abraham's son Ishmael by his slave Hagar, as opposed to his son Isaac by Sarah through whom Judaism comes. Abraham is believed to have been a great prophet, as well as having been the person who (with Ishmael) either discovered or partially built or totally built (depending on which accounts you believe) the kaaba in Mecca. Another interesting difference is that it's assumed by some (many?) Muslims that Ishmael was the son that Abraham almost sacrificed, though also acknowledged that at least in the Qur'an, said son isn't actually named.