Musnad Abu Ya'la al-Mawsili 91:1

Salih ibn Hatim ibn Wardan narrated to us, Yazid ibn Zuray' narrated to us, Dawud ibn Abi Hind narrated to us, from Abdullah ibn Qays, from al-Harith ibn Waqish, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "There are no two Muslims between whom four [children] die, except that Allah will cause them both to enter Paradise by the grace of His mercy." A man said: "O Messenger of Allah, and three?" He said: "And three." He said: "And two?" He said: "And two." He said: "And indeed, there are those from my Ummah who will cause more than [the tribe of] Mudar to enter [Paradise] through their intercession."