Musnad Ahmad 31:381

Abu Ahmad narrated to us, Kathir bin Zayd narrated to us, from Rabih bin Abd al-Rahman bin Abi Sa'id al-Khudri, from his father, from his grandfather, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "There is no ablution for the one who does not mention the name of Allah over it."