Narrated Abdullah ibn Sunabihi:

AbuMuhammad fancies that witr prayer is essential. (Hearing this) Ubadah ibn as-Samit said: AbuMuhammad was wrong. I bear witness that I heard the Messenger of Allah ﷺ say: Allah, the Exalted, has made five prayers obligatory. If anyone performs ablution for them well, offers them at their (right) time, and observes perfectly their bowing and submissiveness in them, it is the guarantee of Allah that He will pardon him; if anyone does not do so, there is no guarantee for him on the part of Allah; He may pardon him if He wills, and punish him if He wills.

حَدَّثَنَا مُحَمَّدُ بْنُ حَرْبٍ الْوَاسِطِيُّ، حَدَّثَنَا يَزِيدُ، - يَعْنِي ابْنَ هَارُونَ - حَدَّثَنَا مُحَمَّدُ بْنُ مُطَرِّفٍ، عَنْ زَيْدِ بْنِ أَسْلَمَ، عَنْ عَطَاءِ بْنِ يَسَارٍ، عَنْ عَبْدِ اللَّهِ بْنِ الصُّنَابِحِيِّ، قَالَ زَعَمَ أَبُو مُحَمَّدٍ أَنَّ الْوِتْرَ، وَاجِبٌ، فَقَالَ عُبَادَةُ بْنُ الصَّامِتِ كَذَبَ أَبُو مُحَمَّدٍ أَشْهَدُ أَنِّي سَمِعْتُ رَسُولَ اللَّهِ ﷺ يَقُولُ
" خَمْسُ صَلَوَاتٍ افْتَرَضَهُنَّ اللَّهُ تَعَالَى مَنْ أَحْسَنَ وُضُوءَهُنَّ وَصَلاَّهُنَّ لِوَقْتِهِنَّ وَأَتَمَّ رُكُوعَهُنَّ وَخُشُوعَهُنَّ كَانَ لَهُ عَلَى اللَّهِ عَهْدٌ أَنْ يَغْفِرَ لَهُ وَمَنْ لَمْ يَفْعَلْ فَلَيْسَ لَهُ عَلَى اللَّهِ عَهْدٌ إِنْ شَاءَ غَفَرَ لَهُ وَإِنْ شَاءَ عَذَّبَهُ " .