It is narrated from Sayyiduna Jabir (may Allah be pleased with him) that Nu’man bin Qawqal came to the Prophet (peace and blessings be upon him) and said, "O Messenger of Allah! If I consider the lawful as lawful and the unlawful as unlawful, perform the obligatory prayers, and fast in Ramadan, and do nothing more than this, can I enter Paradise?" The Prophet (peace and blessings be upon him) said, "Yes." So he said, "By Allah, I will not add anything to this from myself."
Hadith Referenceمسند احمد / مسند المكثرين من الصحابة / 14747
Hadith Gradingحکم دارالسلام:حديث صحيح، م: 15، وهذا إسناد ضعيف من أجل ابن لهيعة، لكنه متابع، وأبو الزبير لم يصرح بالتحديث، وقد توبع هو أيضا