Musannaf Ibn Abi Shayba 6:1081

Ghundar narrated to us, from Shu'bah, from Qays, from Abu Ramlah, from Ubayd Allah ibn Muslim, from Mu'adh ibn Jabal, from the Prophet (peace and blessings of Allah be upon him), that he said: "The one with three [children] has made [Paradise] obligatory." They said: "And the one with two, O Messenger of Allah?" He said: "And the one with two."