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." (RU)
English reference (RU): Vol. 1, Book 1, Hadith 598 (RU)
Arabic reference (RU): Book 1, Hadith 641 (RU)