pre-Islamic customs of slaying children, 6:137, 6:140

And so to many of the Mushrikun (polytheists - see V.2:105) their (Allah's so­called) "partners" have made fair-seeming the killing of their children, in order to lead them to their own destruction and cause confusion in their religion. And if Allah had willed they would not have done so. So leave them alone with their fabrications." (6:137)

Indeed lost are they who have killed their children, from folly, without knowledge, and have forbidden that which Allah has provided for them, inventing a lie against Allah. They have indeed gone astray and were not guided." (6:140)