The Prophet (may Allah's peace and blessings be upon him) would approach all of his wives and then take one ritual bath

This Hadīth tells about the Prophet's good treatment to his wives. He would have sexual intercourse with all of them during one night so as to please them all. Meanwhile, he would have only one ritual bath, because washing is not obligatory between two incidents of sexual intercourse, whether it takes place with the same wife or another one, as indicated by the Hadīth.