Ka'b ibn Lu'ayy was an ancestor of the Prophet ﷺ, son of Lu'ayy and father of Murrah, within the agreed line to Adnan. His descendants, with those of his brother Amir ibn Lu'ayy, made up the Quraysh, and "the sons of Ka'b ibn Lu'ayy" was a name for them; the Prophet ﷺ began his first public warning by calling out to the tribe of Ka'b ibn Lu'ayy.