Mishkat al-Masabih 3 Purification كتاب الطهارة 159

وَعَنْ أَنَسٍ قَالَ: كَانَ النَّبِيُّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ يطوف على نِسَائِهِ وَبِغسْلِ وَاحِد. رَوَاهُ مُسلم

Anas said that the Prophet used to have intercourse with his wives, with only a single washing. Muslim transmitted it.