The expression “god of the father(s)” is mentioned in textual sources from the whole area of the Fertile Crescent, between the third and first millennium B.C. The god of the fathers — aside from assumptions of the tutelary deity as a god of ancestors or a god who is a deified ancestor — was situated in the centre and the very core of religious life among all peoples that lived in the ancient Near East. This paper is focused on the importance of the cult of Ilaba in the royal families of the ancient Near East. It also investigates the possible source and route of spreading of the cult of Ilaba, which could have been created in southern Mesopotamia, then brought to other areas. Hypothetically, it might have come to the Near East from the upper Euphrates.