>> arabs today trace their lineage right back to abraham through ishmael. every year, millions of christians make their pilgrimage to the place where they believe abraham made his home. mecca in saudi arabia. here, muslims also believe abraham came to visit ishmael and together they built ishmael's first house and they built the first house of worship. the bible doesn't mention mecca. instead, it tells us abraham finally found a permanent home in kanaan. he and sarah had settled into their old age, perhaps at last enjoying some measure of tranquility after all they had endured. then, unexpected visitors appeared and changed their lives again. >> abraham looks up. he sees three men. he greets them, he welcomes them. sarah hurries to make them a meal. hospitality is quintessential. >> in nomadic cultures,