Among the descendants of Prophet Abraham/Ibrahim (AS), Imam Ali (AS) belonged to the line of Quraish.

Imam Ali bin Abi Taleb (AS) the Commander of the Faithful (Amir Al-Muminin) was the first cousin of Holy Prophet Muhammad Mustafa (PBUH).

His father is Abu Talib (RA) the son of Abdul Muttalib (RA). The father of Holy Prophet Muhammad (PBUH) is Abdullah (RA) son of Abdul Muttalib (RA).

Abu Talib (RA) and Abdullah (RA) were brothers from the father Abdul Muttalib (who was called Shaybah) ibn Hashim.

Source: en.shafaqna.com