Musnad Ahmad 28:342

Waki' narrated to us, al-A'mash narrated to us, from Shaqiq, and Ibn Numayr said: al-A'mash informed us, from Shaqiq, from Masruq, from Abdullah ibn Amr, who said: The Messenger of Allah (peace and blessings of Allah be upon him) was neither obscene nor did he seek obscenity. He used to say: "Among the best of you are those with the best characters." Ibn Numayr said: "Indeed, the best of you are those with the best characters."