Musannaf Ibn Abi Shayba 3:6326

Ibn Fudayl narrated to us, from Yunus, from ‘Amr ibn Yazid ibn Abi Maryam, from Anas ibn Malik, who said: The Messenger of Allah (may Allah bless him and grant him peace) said: "Whoever sends blessings upon me once, Allah will send ten blessings upon him and will remit ten of his sins."