Authentic
graded by Al-Albani
Mishkat al-Masabih 455
Narrator:Anas ibn Mālik
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.
Cited in Mishkat al-Masabih (No. 455).