Musnad Abu Ya'la al-Mawsili 155:192

Abu Bakr ibn Abi Shaybah narrated to us, Abu Khalid al-Ahmar narrated to us, from Hisham, from Ibn Sirin, from Abu Hurayrah, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "What do you consider the *raqūb* (childless person) among you to be?" They said: "The one who has no children." He said: "No, rather it is the one who has no *faraṭ* (children who have died before him)."