Hadith: O Messenger of Allah, I left no minor or major sin without committing it." He said: "Do you not testify that there is no god but Allah and that Muhammad is the Messenger of Allah?

عَنْ أَنَسٍ رضي الله عنه قَالَ:
جَاءَ رَجُلٌ إِلَى النَّبِيِّ صَلَّى اللهُ عَلَيْهِ وَسَلَّمَ فَقَالَ: يَا رَسُولَ اللهِ، مَا تَرَكْتُ حَاجَّةً وَلَا دَاجَّةً إِلَّا قَدْ أَتَيْتُ، قَالَ: «أَلَيْسَ تَشْهَدُ أَنْ لَا إِلَهَ إِلَّا اللهُ وَأَنَّ مُحَمَّدًا رَسُولُ اللهِ؟» ثَلَاثَ مَرَّاتٍ. قَالَ: نَعَمْ، قَالَ: «فَإِنَّ ذَلِكَ يَأْتِي عَلَى ذَلِكَ».
[صحيح] - [رواه أبو يعلى والطبراني والضياء المقدسي] - [الأحاديث المختارة للضياء المقدسي: 1773]

Anas (may Allah be pleased with him) reported:
A man came to the Prophet (may Allah’s peace and blessings be upon him) and said: "O Messenger of Allah, I left no minor or major sin without committing it." He said: "Do you not testify that there is no god but Allah and that Muhammad is the Messenger of Allah?" He repeated the question three times. He replied: 'Yes.' The Prophet (may Allah’s peace and blessings be upon him) said: "This prevails over that."
Sahih/Authentic. - [Abu Ya‘laa]

Explanation

A man came to the Prophet (may Allah's peace and blessings be upon him) and said: O Messenger of Allah, I committed all sins and misdeeds and left no minor or major sin except that I did it. Can I be forgiven? The Prophet (may Allah's peace and blessings be upon him) said to him: Do you not testify that there is no god but Allah and that Muhammad is the Messenger of Allah? He asked the question three times. The man replied in the affirmative. Thereupon, the Prophet (may Allah's peace and blessings be upon him) told him about the merit of the two testimonies of faith and how they expiate sins, and that repentance erases past misdeeds.