Ubayy b. Ka’b said :The verdict that water (bath) is necessary when there is emission given by the people (in the early days of Islam) was due to the concession granted by the Messenger of Allah in the beginning of Islam. He then commanded to take a bath (in such a case).Abu Dawud said : By Abu Ghassan is meant Muhammad b. mutarrif.
حَدَّثَنَا مُحَمَّدُ بْنُ مِهْرَانَ الْبَزَّازُ الرَّازِيُّ، حَدَّثَنَا مُبَشِّرٌ الْحَلَبِيُّ، عَنْ مُحَمَّدٍ أَبِي غَسَّانَ، عَنْ أَبِي حَازِمٍ، عَنْ سَهْلِ بْنِ سَعْدٍ، حَدَّثَنِي أُبَىُّ بْنُ كَعْبٍ، أَنَّ الْفُتْيَا الَّتِي، كَانُوا يُفْتُونَ أَنَّ الْمَاءَ مِنَ الْمَاءِ كَانَتْ رُخْصَةً رَخَّصَهَا رَسُولُ اللَّهِ صلى الله عليه وسلم فِي بَدْءِ الإِسْلاَمِ ثُمَّ أَمَرَ بِالاِغْتِسَالِ بَعْدُ .
AbuDaud
Purification (Kitab Al-Taharah) • Hadith 215