Repentance

From Quran

يَٰٓأَيُّهَا ٱلَّذِينَ ءَامَنُواْ تُوبُوٓاْ إِلَى ٱللَّهِ تَوۡبَةٗ نَّصُوحًا عَسَىٰ رَبُّكُمۡ أَن يُكَفِّرَ عَنكُمۡ سَيِّـَٔاتِكُمۡ وَيُدۡخِلَكُمۡ جَنَّٰتٖ تَجۡرِي مِن تَحۡتِهَا ٱلۡأَنۡهَٰرُ يَوۡمَ لَا يُخۡزِي ٱللَّهُ ٱلنَّبِيَّ وَٱلَّذِينَ ءَامَنُواْ مَعَهُۥۖ نُورُهُمۡ يَسۡعَىٰ بَيۡنَ أَيۡدِيهِمۡ وَبِأَيۡمَٰنِهِمۡ يَقُولُونَ رَبَّنَآ أَتۡمِمۡ لَنَا نُورَنَا وَٱغۡفِرۡ لَنَآۖ إِنَّكَ عَلَىٰ كُلِّ شَيۡءٖ قَدِيرٞ

سورة االتحريم، ٨ .

O you who have believed, repent to Allāh with sincere repentance. Perhaps your Lord will remove from you your misdeeds and admit you into gardens beneath which rivers flow [on] the Day when Allāh will not disgrace the Prophet and those who believed with him. Their light will proceed before them and on their right; they will say, Our Lord, perfect for us our light and forgive us. Indeed, You are over all things competent.

Surah At-Taḥrīm: 8

Hadith: Arabic Text followed by English Translation. 

عن الأغر بن يسار المزنى رضي الله عنه قال‏:‏ قال رسول الله صلى الله عليه وسلم‏:‏ ‏

ياأيها الناس توبوا إلى الله واستغفروه فإنى أتوب في اليوم مائه مرة‏

رواه مسلم ٢٧٠٢

Al-Agharr bin Yasar Al-Muzani (May Allah be pleased with him) narrated that:
The Messenger of Allah (ﷺ) said:

By Him in Whose Hand is my life, if you were not to commit sin, Allah would sweep you out of existence and He would replace (you by) those people who would commit sin and seek forgiveness from Allah, and He would have pardoned them.

Narrated by Muslim, 2702