Murrah ibn Ka'b (Arabic: مُرَّة ٱبْن كَعْب) ibn Luay ibn Ghalib ibn Fihr ibn Malik was a man from Quraysh tribe, supposed to have lived in the 4th century.[1] He was the sixth-in-line of Muhammad's grandfathers. He is the common ancestor of all four of Muhammad's grandparents. He is also the common ancestor of six of Muhammad's eight great-grandparents. He is also the common ancestor of Muhammad and his friend Abu Bakr.