This verse is: "Verily, those who conceal the clear signs and the guidance which we have sent down...)" (2:159). I heard the Prophet ﷺ saying, 'If a man performs ablution perfectly and then offers the compulsory congregational prayer, Allah will forgive his sins committed between that (prayer) and the (next) prayer till he offers it.  

أَلاَ أُحَدِّثُكُمْ حَدِيثًا لَوْلاَ آيَةٌ مَا حَدَّثْتُكُمُوهُ سَمِعْتُ النَّبِيَّ ﷺ يَقُولُ لاَ يَتَوَضَّأُ رَجُلٌ فَيُحْسِنُ وُضُوءَهُ وَيُصَلِّي الصَّلاَةَ إِلاَّ غُفِرَ لَهُ مَا بَيْنَهُ وَبَيْنَ الصَّلاَةِ حَتَّى يُصَلِّيَهَا قَالَ عُرْوَةُ الآيَةُ {إِنَّ الَّذِينَ يَكْتُمُونَ مَا أَنْزَلْنَا مِنَ الْبَيِّنَاتِ}  

By Allah, I am narrating to you a hadith had there not been this verse in the Book of Allah. I would not have narrated it to you. Verily I heard the Messenger of Allah ﷺ say: Not a person is there who performed ablution, and did it well, then offered prayer, but his sins (which he committed) were not pardoned between the prayer that he offered and the next one. 'Urwa said: The verse is this:" Those who suppress the clear proofs and the guidance which We have sent down"... to His words:" the Cursers" (ii. 15).  

فَلَمَّا تَوَضَّأَ عُثْمَانُ قَالَ وَاللَّهِ لأُحَدِّثَنَّكُمْ حَدِيثًا وَاللَّهِ لَوْلاَ آيَةٌ فِي كِتَابِ اللَّهِ مَا حَدَّثْتُكُمُوهُ إِنِّي سَمِعْتُ رَسُولَ اللَّهِ ﷺ يَقُولُ لاَ يَتَوَضَّأُ رَجُلٌ فَيُحْسِنُ وُضُوءَهُ ثُمَّ يُصَلِّي الصَّلاَةَ إِلاَّ غُفِرَ لَهُ مَا بَيْنَهُ وَبَيْنَ الصَّلاَةِ الَّتِي تَلِيهَا قَالَ عُرْوَةُ الآيَةُ { إِنَّ الَّذِينَ يَكْتُمُونَ مَا أَنْزَلْنَا مِنَ الْبَيِّنَاتِ وَالْهُدَى} إِلَى قَوْلِهِ { اللاَّعِنُونَ}  

Yahya related to me from Malik from Hisham ibn Urwa from his father from Humran, the mawla of Uthman ibn Affan, that Uthman ibn Affan was once sitting on the Maqaid (the benches surrounding the Madina Mosque, or else a stone near Uthman ibn Affan's house where he sat to discuss with people), when the muadhdhin came and told him that it was time for the asr prayer. He called for water and did wudu. Then he said, "By Allah, I shall tell you something which I would not tell you if it were not in the Book of Allah. I heard the Messenger of Allah ﷺ say, 'If a man does wudu, and makes sure he does it correctly, and then does the prayer, he will be forgiven everything that he does between then and the time when he prays the next prayer.' " Yahya said that Malik said, "I believe he meant this ayat - 'Establish prayer at the two ends of the day and in some watches of the night. Good actions take away wrong actions. That is a reminder for those who remember.' " (Sura 11 ayat 114).  

أَنَّهُ فِي كِتَابِ اللَّهِ مَا حَدَّثْتُكُمُوهُ ثُمَّ قَالَ سَمِعْتُ رَسُولَ اللَّهِ ﷺ يَقُولُ مَا مِنِ امْرِئٍ يَتَوَضَّأُ فَيُحْسِنُ وُضُوءَهُ ثُمَّ يُصَلِّي الصَّلاَةَ إِلاَّ غُفِرَ لَهُ مَا بَيْنَهُ وَبَيْنَ الصَّلاَةِ الأُخْرَى حَتَّى يُصَلِّيَهَا  

My father told me that Humran told him: ʿUthman ؓ did wudoo’ in al-Balat (a paved area in Madinah) then he said, i shall tell you a hadeeth that I heard from the Messenger of Allah ﷺ . Were it not for a verse in the Book of Allah, I would not have told you it. I heard the Prophet ﷺ say: ʿWhoever does wudoo’ and does it well, then goes in and prays, his sins between that prayer and the next will be forgiven, until he prays [the second prayer].”  

لَأُحَدِّثَنَّكُمْ حَدِيثًا سَمِعْتُهُ مِنْ رَسُولِ اللهِ ﷺ لَوْلَا آيَةٌ فِي كِتَابِ اللهِ مَا حَدَّثْتُكُمُوهُ سَمِعْتُ النَّبِيَّ ﷺ يَقُولُ مَنْ تَوَضَّأَ فَأَحْسَنَ الْوُضُوءَ ثُمَّ دَخَلَ فَصَلَّى غُفِرَ لَهُ مَا بَيْنَهُ وَبَيْنَ الصَّلاةِ الْأُخْرَى حَتَّى يُصَلِّيَهَا  

My father told me that Humran told him: ʿUthman ؓ did wudoo’ in al-Balat (a paved area in Madinah) then he said, i shall tell you a hadeeth that I heard from the Messenger of Allah ﷺ . Were it not for a verse in the Book of Allah, I would not have told you it. I heard the Prophet ﷺ say: ʿWhoever does wudoo’ and does it well, then goes in and prays, his sins between that prayer and the next will be forgiven, until he prays [the second prayer].” (Using translation from Aḥmad 400)   

لَأُحَدِّثَنَّكُمْ حَدِيثًا لَوْلَا آيَةٌ فِي كِتَابِ اللَّهِ لَمَّا حَدَّثْتُكُمُوهُ ثُمَّ قَالَ سَمِعْتُ رَسُولَ اللَّهِ ﷺ يَقُولُ «مَا مِنِ امْرِئٍ يَتَوَضَّأُ فَيُحْسِنُ الْوُضُوءَ ثُمَّ يُصَلِّي الصَّلَاةَ إِلَّا غُفِرَ لَهُ مَا بَيْنَهُ وَبَيْنَ الصَّلَاةِ الْأُخْرَى حَتَّى يُصَلِّيَهَا»