Bath can be Delayed but with Ablution

Narrated Abu Salamah (radi Allahu anhu): “I asked Aisha (radi Allahu anha), ‘Did the Prophet (sal Allahu alaihi wa sallam) use to sleep while he was Junub?’ She replied, ‘Yes, but he used to perform ablution (before going to bed).’” [The Book of Ghusl: Sahih Bukhari]

This hadith informs us that a Junub (person in a state of impurity from intercourse) may stay and sleep in that condition without taking a bath, but with ablution. The ghusl (bath) must, however, be taken in time to perform the next Salah.