Musnad Ahmad 30:3195

Isma'il narrated to us, from al-Jurayri, from Khalid ibn Ghallaq al-'Ayshi, who said: I stayed with Abu Hurayrah. He said: A son of mine died, and I grieved over him. So I said: Have you heard anything from your intimate friend [the Prophet] that would console our souls regarding our dead? He said: Yes, I heard him, may Allah bless him and grant him peace, say: "Their little ones are the little creatures of Paradise."