Sahih Muslim Book - 1, Hadith - 110

و حَدَّثَنِي سَلَمَةُ بْنُ شَبِيبٍ حَدَّثَنَا الْحَسَنُ بْنُ أَعْيَنَ حَدَّثَنَا مَعْقِلٌ وَهُوَ ابْنُ عُبَيْدِ اللَّهِ عَنْ أَبِي الزُّبَيْرِ عَنْ جَابِرٍ أَنَّ رَجُلًا سَأَلَ رَسُولَ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ فَقَالَ أَرَأَيْتَ إِذَا صَلَّيْتُ الصَّلَوَاتِ الْمَكْتُوبَاتِ وَصُمْتُ رَمَضَانَ وَأَحْلَلْتُ الْحَلَالَ وَحَرَّمْتُ الْحَرَامَ وَلَمْ أَزِدْ عَلَى ذَلِكَ شَيْئًا، أَأَدْخُلُ الْجَنَّةَ؟ قَالَ نَعَمْ قَالَ وَاللَّهِ لَا أَزِيدُ عَلَى ذَلِكَ شَيْئًا.

It was narrated from Jabir that a man asked the Messenger of Allah (s.a.w): "Do you think that if I offer the prescribed Salat, observe fast (the month of) Ramadan, regard as permissible that which is lawful and regard as forbidden that which is unlawful, and I do not do any more than that, I will enter Paradise?" He (s.a.w) said: "Yes." He said: "By Allah, I shall not do any more than that."