If one forgets to perform wuzoo and remembers afterwards...

If one forgets to perform wuzoo and remembers afterwards, then he can perform tayammum on the sheet with which he is covering himself. If after this form of purification and before going to bed he thinks and praises God until he is asleep, then his sleep will be as good as prayer. According to Hazrat Ali (a.s.), a muslim should not sleep in the state of janabat and without wuzoo.

If water is not available for bathing or wuzoo, then one should perform tayammum as the spirit of the momin travels towards Heaven while he is sleeping and according to its cleanliness and purification it is received by God. It is blessed and rewarded by God. And if he dies while sleeping, then he gets a place in the blessings of God. If he is alive, then God sends angels to guard him.

According to another tradition, the Holy Prophet (s.a.w.a.) asked his followers that who amongst them kept fasts all the year round. Hazrat Salman-e-Farsi replied that he fasted all the year round. The Holy Prophet (s.a.w.a.) questioned who had spent his nights in prayers, being awake all through. Again Salman replied that he was the man in accordance with the description. Then, looking at all the assembled companions, the Holy Prophet (s.a.w.a.) asked who reads one Quran every day.

All kept quiet except Salman who replied in the affirmative. One of the assembled was furious at Salman and said to others that Salman is showing off and lieing as he had seen Salman many a days not observing fast, many a nights sleeping instead of praying and also not completing a Quran each day. The Holy Prophet (s.a.w.a.) intervened and said that Salman is like Lukman (Soloman the Great) and whosoever doubts him should question him directly and he would reply.

Then he immediately questioned Salman and Salman gave the following answer; every month he fasted on 13th, 14th and 15th. God has said that he will reward ten times any good act; therefore, his three fasts are equal to thirty fasts and in this manner he fasts for one month it will be like keeping fasts all the year round. Besides, he fasted all through the month of Shaban and Ramzan in this way he keeps more fasts when each fast will be multiplied by ten.