Hadithcore
Sunan an-Nasa'i, 46
sahih· Darussalam

It was narrated that 'Aishah said:

"Tell your husbands to clean themselves with water, for I am too shy to tell them myself. The Messenger of Allah (ﷺ) used to do that."

أَخْبَرَنَا قُتَيْبَةُ، قَالَ حَدَّثَنَا أَبُو عَوَانَةَ، عَنْ قَتَادَةَ، عَنْ مُعَاذَةَ، عَنْ عَائِشَةَ، أَنَّهَا قَالَتْ مُرْنَ أَزْوَاجَكُنَّ أَنْ يَسْتَطِيبُوا بِالْمَاءِ فَإِنِّي أَسْتَحْيِيهِمْ مِنْهُ إِنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم كَانَ يَفْعَلُهُ ‏.‏

References2 variants
In-Book Reference
Book 1, Hadith 46
English Reference
Vol. 1, Book 1, Hadith 46