Musnad Ahmad 626:86

Abu al-Walid and 'Affan narrated to us, they said: 'Ubayd Allah ibn Iyad narrated to us, Iyad narrated to us, from Suwayd ibn Sarhan, from al-Mughirah ibn Shu'bah, that the Messenger of Allah (peace and blessings of Allah be upon him) ate food, then the prayer was called, so he stood up, and he had performed ablution before that. I brought him water so that he might perform ablution from it, but he rebuked me and said: "Get behind me." By Allah, that distressed me. Then he prayed, so I complained about that to 'Umar. He said: "O Prophet of Allah, indeed al-Mughirah is distressed by your rebuking him, and he fears that you might have something against him in your heart." The Prophet (peace and blessings of Allah be upon him) said: "There is nothing in my heart against him except good, but he brought me water so that I might perform ablution, and I had only eaten food; and if I had done so, the people would have done that after me."