Musnad Ahmad 1244:7

Isma'il ibn Ibrahim narrated to us, he said: Ma'mar informed us, from al-Zuhri, from Humayd ibn 'Abd al-Rahman, from his mother, Umm Kulthum bint 'Uqbah, she said: I heard the Messenger of Allah, peace and blessings of Allah be upon him, saying: "The liar is not the one who reconciles between people, so he says something good or conveys something good."