The Prophet used to go round to all his wives with one bath.
Sunan Ibn Majah Book 1, Hadith 322
← Previous Hadith "The Messenger of Allah said: 'If anyone of you has intercourse with his wife, then he wants to do it again, let him perform ablution.'"

Sunan Ibn Majah Book 1, Hadith 321 Next Hadith → "I put out water for the Messenger of Allah for a bath, and he had a bath after going to all of his wives in one night."

Sunan Ibn Majah Book 1, Hadith 323