Musnad Abu Ya'la al-Mawsili 109:296

Ibn Numayr narrated to us, my father narrated to us, from al-A’mash, from Abu Sufyan, from Jabir, who said: A man from the Ansar, who was called al-Nu’man ibn Qawqal, came to the Prophet (may Allah bless him and grant him peace) and said: "O Messenger of Allah, have you considered if I perform the prescribed prayers, treat the lawful as lawful, and treat the forbidden as forbidden, and I do not add anything to that, shall I enter Paradise?" He said: "Yes."