Musannaf Ibn Abi Shayba 21:620

Yazid ibn Harun narrated to us, from Hammad ibn Salamah, from Asim ibn Bahdalah, from Abu Salih, from Abu Hurairah, from the Prophet, peace and blessings of Allah be upon him, who said: "Indeed, a degree is raised for a man in Paradise, so he says: 'O my Lord, from where did this come to me?' It is said: 'By your child's seeking forgiveness for you.'"