Musnad Ahmad 32:593

'Abd al-Samad narrated to us, 'Abd al-Malik al-Numayri narrated to us, Thabit narrated to us, from Anas, that the Prophet, peace and blessings of Allah be upon him, said: "There is no Muslim man who has three of his children die before they reach the age of puberty, except that Allah will cause his parents to enter Paradise by the grace of His mercy toward them."