The place where allah promised abraham that his descendants would become a great nation through his son ishmael is

I believe the answer is: the Well of Zamzam

It is said in the holy Quran that after After Abraham left his Son and wife at the Well of Zamzam, the place miraculously filled with water that could sustan the life of living organisms. Today, this place is mostly known as the location for Masjid al-Haram in Mecca, which regarded as one of the holy place for muslims.