Hadith:

Ubadah ibn As-Samit reported: I heard the Messenger of Allah, peace and blessings be upon him, saying, “Allah the Exalted has made five prayers obligatory. Whoever performs their ablution well, prays them at their proper time, and completes their bowing and their reverence due, then Allah has promised to forgive him. Whoever does not do so has no promise from Allah; if He wills, He will forgive him, or if He wills, He will punish Him.”

Source: Sunan Abu Dawud 425

Grade: Sahih (authentic) according to An-Nawawi

فَقَالَ عُبَادَةُ بْنُ الصَّامِتِ أَشْهَدُ أَنِّي سَمِعْتُ رَسُولَ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ يَقُولُ خَمْسُ صَلَوَاتٍ افْتَرَضَهُنَّ اللَّهُ تَعَالَى مَنْ أَحْسَنَ وُضُوءَهُنَّ وَصَلَّاهُنَّ 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