On the authority of Abu Abdullah Jabir bin Abdullah al-Ansaree (may Allah be pleased with him) that:
A man questioned the Messenger of Allah (peace and blessings of Allah be upon him) and said, "Do you think that if I perform the obligatory prayers, fast in Ramadhan, treat as lawful that which is halal, and treat as forbidden that which is haram, and do not increase upon that [in voluntary good deeds], then I shall enter Paradise?" He (peace and blessings of Allah be upon him) replied, "Yes."[Muslim]
Reference: 40 Hadith Nawawi 22
English translation: Hadith 22