Hadithcore
Sunan Ibn Majah, 609
sahih· Darussalam

Ubayy bin Ka'b said:

"That was a concession that was granted in the early days of Islam, then we were commanded to have a bathe after that."

حَدَّثَنَا مُحَمَّدُ بْنُ بَشَّارٍ، حَدَّثَنَا عُثْمَانُ بْنُ عُمَرَ، أَنْبَأَنَا يُونُسُ، عَنِ الزُّهْرِيِّ، قَالَ قَالَ سَهْلُ بْنُ سَعْدٍ السَّاعِدِيُّ أَنْبَأَنَا أُبَىُّ بْنُ كَعْبٍ، قَالَ إِنَّمَا كَانَتْ رُخْصَةً فِي أَوَّلِ الإِسْلاَمِ ثُمَّ أُمِرْنَا بِالْغُسْلِ بَعْدُ ‏.‏

References2 variants
In-Book Reference
Book 1, Hadith 343
English Reference
Vol. 1, Book 1, Hadith 609