حَدَّثَنَا هِشَامُ بْنُ عَمَّارٍ، حَدَّثَنَا يَحْيَى بْنُ حَمْزَةَ، حَدَّثَنِي عُتْبَةُ بْنُ أَبِي حَكِيمٍ، حَدَّثَنِي طَلْحَةُ بْنُ نَافِعٍ، حَدَّثَنِي أَبُو أَيُّوبَ الأَنْصَارِيُّ، أَنَّ النَّبِيَّ ـ صلى الله عليه وسلم ـ قَالَ ‏"‏ الصَّلَوَاتُ الْخَمْسُ وَالْجُمُعَةُ إِلَى الْجُمُعَةِ وَأَدَاءُ الأَمَانَةِ كَفَّارَةٌ لِمَا بَيْنَهَا ‏"‏ ‏.‏ قُلْتُ وَمَا أَدَاءُ الأَمَانَةِ قَالَ ‏"‏ غُسْلُ الْجَنَابَةِ فَإِنَّ تَحْتَ كُلِّ شَعَرَةٍ جَنَابَةً ‏"‏ ‏.‏

Abu Ayyub Al-Ansari narrated that: The Prophet said: "The five daily prayers, from one Friday to the next, and fulfilling the trust are all expiation for whatever (sins) come between them." I said: "What is fulfilling the trust?" He said: Having a bath to cleanse oneself from sexual impurity, for under every hair there is the state of sexual impurity." Translation Not Available

Book Ref: Sunan Ibn Majah Book 1 Hadith 598
Web Ref:  Sunan Ibn Majah Vol 1 Book 1 Hadith 598