Musnad Ahmad 528:7

'Umar ibn Harun narrated to us, from Thawr ibn Yazid, from Shurayh, from Jubayr ibn Nufayr al-Hadrami, from Nawwas ibn Sam'an, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "It is a great betrayal that you tell your brother a statement in which he believes you, while you are lying to him."