كتاب الطهارة
2
The Book of Purification
(5)
Chapter: The five daily prayers, from one Jumu`ah to the next, and from one Ramadan to the next, are an expiation for whatever (sins) come in between, so long as one avoids major sins
(5)
باب الصَّلَوَاتُ الْخَمْسُ وَالْجُمُعَةُ إِلَى الْجُمُعَةِ وَرَمَضَانُ إِلَى رَمَضَانَ مُكَفِّرَاتٌ لِمَا بَيْنَهُنَّ مَا اجْتُنِبَتِ الْكَبَائِرُ.

Abu Huraira reported that the Messenger of Allah (ﷺ) said:

The five (daily) prayers and one Friday prayer to (the next) Friday prayer are expiations (for the sins committed in the intervals) between them.
حَدَّثَنِي نَصْرُ بْنُ عَلِيٍّ الْجَهْضَمِيُّ، أَخْبَرَنَا عَبْدُ الأَعْلَى، حَدَّثَنَا هِشَامٌ، عَنْ مُحَمَّدٍ، عَنْ أَبِي هُرَيْرَةَ، عَنِ النَّبِيِّ صلى الله عليه وسلم قَالَ ‏ "‏ الصَّلَوَاتُ الْخَمْسُ وَالْجُمُعَةُ إِلَى الْجُمُعَةِ كَفَّارَاتٌ لِمَا بَيْنَهُنَّ ‏"‏ ‏.‏
Reference : Sahih Muslim 233b
In-book reference : Book 2, Hadith 18
USC-MSA web (English) reference : Book 2, Hadith 449
  (deprecated numbering scheme)