Sunan an-Nasa'i, Volume 1, Book 5, Hadith 460 (DarusSalam) ⓘ

It was narrated that Anas said: "A man asked the Messenger of Allah: 'O Messenger of Allah, how many prayers has Allah enjoined upon His slaves?' He said: 'Allah has enjoined upon His slaves (five) prayers.' He said: 'O Messenger of Allah, is there anything before them or after them?' He said: 'Allah has enjoined upon His salves (five) prayers.' The man swore that he would not do anything more or less than that. The Messenger of Allah said: 'If he is speaking the truth he will most certainly enter Paradise.'"

أَخْبَرَنَا قُتَيْبَةُ، قَالَ حَدَّثَنَا نُوحُ بْنُ قَيْسٍ، عَنْ خَالِدِ بْنِ قَيْسٍ، عَنْ قَتَادَةَ، عَنْ أَنَسٍ، قَالَ سَأَلَ رَجُلٌ رَسُولَ اللَّهِ صلى الله عليه وسلم فَقَالَ يَا رَسُولَ اللَّهِ كَمِ افْتَرَضَ اللَّهُ عَزَّ وَجَلَّ عَلَى عِبَادِهِ مِنَ الصَّلَوَاتِ قَالَ ‏"‏ افْتَرَضَ اللَّهُ عَلَى عِبَادِهِ صَلَوَاتٍ خَمْسًا ‏"‏ ‏.‏ قَالَ يَا رَسُولَ اللَّهِ هَلْ قَبْلَهُنَّ أَوْ بَعْدَهُنَّ شَيْئًا قَالَ ‏"‏ افْتَرَضَ اللَّهُ عَلَى عِبَادِهِ صَلَوَاتٍ خَمْسًا ‏"‏ ‏.‏ فَحَلَفَ الرَّجُلُ لاَ يَزِيدُ عَلَيْهِ شَيْئًا وَلاَ يَنْقُصُ مِنْهُ شَيْئًا قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم ‏"‏ إِنْ صَدَقَ لَيَدْخُلَنَّ الْجَنَّةَ ‏"‏ ‏.‏