Musnad Ahmad 1023:1

Abu al-Nadr narrated to us, al-Mubarak narrated to us, al-Hasan narrated to us, that a sheikh from Banu Sulayt informed him, saying: I came to the Messenger of Allah, peace and blessings of Allah be upon him, to speak to him regarding some captives of ours taken during the Jahiliyyah. I found him sitting, and there was a circle of people surrounding him, and he was speaking to the people. He was wearing a thick Qatari waist-wrapper. The first thing I heard him say, while gesturing with his two fingers, was: "The Muslim is the brother of the Muslim; he does not wrong him, nor does he forsake him. Taqwa (piety) is here, Taqwa is here." He said: Meaning, in the heart.