Sunan of Abu Dawood Book 1, Hadith 247

حَدَّثَنَا قُتَيْبَةُ بْنُ سَعِيدٍ، حَدَّثَنَا أَيُّوبُ بْنُ جَابِرٍ، عَنْ عَبْدِ اللَّهِ بْنِ عُصْمٍ، عَنْ عَبْدِ اللَّهِ بْنِ عُمَرَ، قَالَ كَانَتِ الصَّلاَةُ خَمْسِينَ وَالْغُسْلُ مِنَ الْجَنَابَةِ سَبْعَ مِرَارٍ وَغَسْلُ الْبَوْلِ مِنَ الثَّوْبِ سَبْعَ مِرَارٍ فَلَمْ يَزَلْ رَسُولُ اللَّهِ صلى الله عليه وسلم يَسْأَلُ حَتَّى جُعِلَتِ الصَّلاَةُ خَمْسًا وَالْغُسْلُ مِنَ الْجَنَابَةِ مَرَّةً وَغَسْلُ الْبَوْلِ مِنَ الثَّوْبِ مَرَّةً ‏.‏

Narrated Abdullah ibn Umar: There were fifty prayers (obligatory in the beginning); and (in the beginning of Islam) washing seven times because of sexual defilement (was obligatory); and washing the urine from the cloth seven times (was obligatory). The Apostle of Allah (ﷺ) kept on praying to Allah until the number of prayers was reduced to five and washing because of sexual defilement was allowed only once and washing the urine from the clothe was also permitted only once