Sunan an-Nasa'i, Volume 1, Book 2, Hadith 343 (DarusSalam) ⓘ
It was narrated that Ibn 'Umar said: "Men and women used to perform Wudu' together during the time of the Messenger of Allah."
أَخْبَرَنَا هَارُونُ بْنُ عَبْدِ اللَّهِ، قَالَ حَدَّثَنَا مَعْنٌ، قَالَ حَدَّثَنَا مَالِكٌ، عَنْ نَافِعٍ، عَنِ ابْنِ عُمَرَ، قَالَ كَانَ الرِّجَالُ وَالنِّسَاءُ يَتَوَضَّئُونَ فِي زَمَانِ رَسُولِ اللَّهِ صلى الله عليه وسلم جَمِيعًا .
also referenced under: Hadith 342 (Reference) & Book 2, Hadith 18 (In-Book)