Is it permissible to perform ablution (wudu') without a full ritual bath (ghusl) for someone who is in a state of major ritual impurity (janabah) and unable to perform ghusl, and the time for prayer has arrived?

A person in a state of major ritual impurity (junub) must perform ghusl (full ritual bath) for prayer, based on the Almighty's saying: (O you who have believed, do not approach prayer while you are intoxicated until you know what you are saying, nor while junub, except when passing through [a prayer area], until you have washed). If water is not available or if one is unable to use it due to illness, then tayammum (dry ablution) becomes obligatory, based on the Almighty's saying: (And if you are ill or on a journey or one of you comes from the place of relieving himself or you have contacted women and find no water, then seek clean earth and wipe over your faces and hands [with it]). As for wudu (partial ablution), it is never sufficient as a substitute for ghusl.

In the case of the questioner, the availability of water necessitates ghusl and does not permit tayammum or wudu as a substitute. One who prays without the obligatory ghusl is like one who abandons prayer, and abandoning prayer carries a grave danger. Some scholars consider such a person to be a disbeliever and to have exited the fold of Islam, while others believe they should be killed as a legal punishment or imprisoned until they pray. This applies if they abandon it out of laziness, not out of denial of its obligation.