Musannaf Ibn Abi Shayba 1:531

Affan narrated to us, he said: Ubayd Allah ibn Iyad narrated to us, he said: Iyad narrated to me, from Suwayd ibn Sarhan, from al-Mughira ibn Shu’ba, that the Messenger of Allah (may Allah bless him and grant him peace) ate food, then the prayer was established. He had already performed ablution before that, so I brought him water to perform ablution. He rebuked me and said: "Get behind me! If I were to do that, the people would do it after me."