Musnad Ahmad 25:416

Ya'qub narrated to us, my father narrated to us, from Ibn Ishaq, who said: Muhammad ibn al-Walid ibn Nuwayfi', the freed slave of the family of al-Zubayr, narrated to me, from Kurayb, the freed slave of Abdullah ibn Abbas, from Abdullah ibn Abbas, that Dammam ibn Tha'labah, the brother of Banu Sa'd ibn Bakr, when he accepted Islam, asked the Messenger of Allah, peace and blessings of Allah be upon him, about the obligatory duties of Islam, regarding prayer and other things. He counted for him the five prayers, not adding anything to them, then the Zakat, then the fasting of Ramadan, then the pilgrimage to the House. Then he informed him of what Allah had forbidden for him. When he finished, he said: "I bear witness that there is no god but Allah, and I bear witness that you are the Messenger of Allah. I will do what you have commanded me to do, neither adding nor subtracting." He said: Then he turned away. The Messenger of Allah, peace and blessings of Allah be upon him, said: "If the man with the two braids is truthful, he will enter Paradise."