Musnad Abu Ya'la al-Mawsili 3:312

Ubayd Allah narrated to us, Bishr ibn al-Mufaddal narrated to us, Abd al-Rahman ibn Thabit ibn Thawban narrated to us, Abda ibn Abi Lubaba narrated to me, he said: I heard Shaqiq ibn Salama saying: I saw Ali performing ablution three times [for each part]. And he said: Thus did the Messenger of Allah, may Allah bless him and grant him peace, perform ablution.