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 ‏.‏
GradeSahih (Darussalam)
English reference : Vol. 1, Book 1, Hadith 609
Arabic reference : Book 1, Hadith 652