Question: Can a person perform salat without wudu'?
ANSWER
Of course not. Having wudu' is one of the conditions of salat. There are fards, sunnats, adabs, and prohibited things in wudu'. If a person performs salat without wudu' though he does not have a good excuse for doing so and though he knows that he does not have wudu', he becomes a disbeliever (kafir).

Question: Though my overwhelming thought of conscious told me that I did not have wudu', I performed salat in that state, anyway. Afterwards, I positively remembered that I had had wudu'. Was the salat I performed in a state of wudu' considered valid?
ANSWER
Supposing a person thinks that he does not have wudu'. If he performs salat in this state and then remembers that he had wudu', he has to repeat this salat. Similarly, one must not begin salat without determining the qibla or without knowing whether the time for salat has begun.

Question: After having performed Salat-u Zuhr, I remembered that I had not had wudu'. Do I have to repeat it?
ANSWER
Yes, you have to repeat it. If one remembers it after the time for the salat has ended, one has to make it up. A salat performed without wudu' though one thinks one has had wudu' will not be valid. Yet one will be given much thawab in return for one’s intention. If a person finds some religiously filthy water and yet thinks it is clean and makes wudu' with it and performs salat, his salat will not be valid because one of its conditions has not been fulfilled; however, he will be given thawab owing to his intention. On the other hand, a salat that is valid because it has been performed with all its conditions fulfilled will not be given any thawab if it has been performed for ostentation and for show. (Ashbah)

Question: I will quote some passages from the book Endless Bliss one by one. I have difficulty in understanding them.

1. It is written in its section concerned with imitating the Maliki Madhhab, "If one remembers later that one forgot to wash a certain part on one’s body, be it a month later, one washes that part immediately. If one does not wash it immediately, one’s ghusl becomes null and void." If one washes that part immediately, one's wudu' and ghusl becomes valid. Will the salats that one performed during a month become valid, too?
ANSWER
Yes, they will. If one does not wash that part immediately, one's wudu' and ghusl will become null and void according to the Maliki Madhhab, so the salats one will perform henceforth with this wudu' and ghusl will not be valid. However, the salats one performed without remembering that one forgot to wash a certain part will be considered valid.

2. It is written in it, "If the imam forgets the fact that he is not in a state of wudu' and leads the congregation in salat in this state and remembers after salat that he led the congregation without wudu', he should inform the ones he remembers to have joined the congregation. Those who have learnt it have to repeat that salat. Those who do not hear it will be pardoned. According to an authentic report, the imam does not have to inform the congregation." How are the salats of those who performed them behind an imam who is without wudu' considered valid?
ANSWER
Their salats are considered valid because they did not deliberately perform salats behind an imam who is without wudu'.

3. It is written in it, "If one's hands and feet has been amputated and one has a wound on one's face too, one offers salat without wudu' because one is unable to do even tayammum, and one is not obligated to repeat the salats [that one performed without wudu']." What difference does it make if one does not perform salat at all rather than perform it without wudu'?
ANSWER
There are also scholars who say that such a person does not have to perform salat. However, it is best to perform it if he or she is able.

4. It is written in it, "A person who sees water after having performed a salat with tayammum does not have to repeat that salat." As he has found water, there is no longer a valid excuse for tayammum. Why doesn't he have to do wudu' with water and repeat that salat?
ANSWER
When he did tayammum, there was no water available. He did tayammum and performed salat with it because there was an Islamically valid reason for doing so. Because he performed that salat in a state of tayammum due to a legitimate Shar'i excuse, he does not have to repeat it.

5. It is written in it, "If najasat splashes on one's clothes or body and if one cannot locate the area smeared with the najasat, it will become clean if one washes the area that one guesses to be the smeared area. If one discovers the correct area after salat, one does not perform the salat again." One discovered later that one had washed the wrong area and found the dirty spot. Then why doesn't one have to repeat the salat that one performed with the dirty garment on?
ANSWER
It is a rule set by our religion, so one cannot question it. Such a person did not perform salat with the dirty garment on deliberately. Rather, he or she performed it, thinking that he or she cleaned the filth on the clothes. This act of his or hers renders the repetition of salat unnecessary.

6. It is written in it, "If there is najasat on one's clothes and one has not seen it and offered salat, one's salat is considered valid. If one notices the najasat after salat, it is not necessary to perform it again." Though one has noticed the najasat, why doesn't one have to perform it again?
ANSWER
Our Master the Messenger of Allah took off his na'l [a kind of shoe with a leather sole and strap] as he was performing salat and stated: “Jabrail alaihis-salam has informed me that the na'l has dirt on it.” Yet he did not repeat that salat. The mujtahid scholars who based the ruling on this event stated that it is not necessary to repeat a salat when this is the case.

7. It is written in it, "You must search for it yourself and then perform salat towards the direction you have decided to be the Qibla. If later you find out that it was the wrong direction, you do not have to perform the salat again." Performing a salat toward the Qibla is compulsory. Then why is a salat performed by omitting one of its compulsory elements not performed again?
ANSWER
By searching for the Qibla, one has carried out the command of Islam. Because one has acted in conformity with what Islam has commanded, one's salat is considered valid, even if one performed it towards a direction other than the Qibla.

8. It is written in it, "If, after inquiring and finding out that a person can be paid zakat and after paying him or her zakat, one learns that he or she is rich or a disbeliever, it will be all right. That is, one does not have to repay it." How can the zakat given to a rich person or a disbeliever be considered permissible?
ANSWER
The giver has done the requisite inquiring. When he or she is fully convinced that the receiver is poor and a Muslim, he or she gives the zakat. His or her inquiring in the beginning absolves him or her of the obligation of repaying it. Likewise, it is written in the book Targhib-us-salat, "If an imam, after leading the congregation [jama'at] in salats for years, says that he is a non-Muslim, the people who performed salats behind him will not have to repeat these salats." The reason why this is so is that our religion judges someone by the way he or she appears to be. Only Allahu ta'ala knows what is hidden in the hearts. He does not question the jama'at about why they could not know that the imam was a non-Muslim.