Musnad Ahmad 258:15

Al-Hakam ibn Nafi’ narrated to us, he said: Isma’il ibn ‘Ayyash narrated to us, from Abu Shaybah Yahya ibn Yazid, from ‘Abd al-Wahhab al-Makki, from ‘Abd al-Wahid ibn ‘Abd Allah al-Nasri, from Wathilah ibn al-Asqa’, he said: I heard the Messenger of Allah, peace and blessings of Allah be upon him, saying: "The blood, honor, and wealth of a Muslim are sacred to another Muslim. The Muslim is the brother of the Muslim; he does not wrong him, nor does he forsake him. And piety is here," and he gestured with his hand toward his chest. He said: "It is sufficient evil for a man that he belittles his Muslim brother."