This hadith discusses what invalidates wudu. The one whose wudu’ is invalidated is not allowed to do anything for which wudu’ is required, such as praying. Purifying oneself after wudu’ has been invalidated is a condition of prayer being valid. In this hadith, Abu Hurayrah (may Allah be pleased with him) tells us that the Prophet (blessings and peace of Allah be upon him) said: “The prayer of one whose wudu’ was invalidated will not be accepted until he does wudu’.” In other words, until he purifies himself with water. Anyone who prays when his wudu’ has been invalidated, his prayer will not be accepted and it is not valid. Abu Hurayrah (may Allah be pleased with him) explained what invalidates wudu’ in this hadith as breaking wind, either silently or loudly; in both cases, it refers to wind being expelled from the back passage. However, this is not the only thing that invalidates wudu’, as urination and defecation both invalidate wudu’ too, and they also come under the heading of minor impurity. Janabah and having intercourse also invalidate wudu’, but they come under the heading of major impurity; and there are other things that invalidate wudu’. He only mentioned one of the things that invalidate wudu’, because he was answering someone who asked him about one whose wudu’ is invalidated whilst he is praying, so he gave an answer concerning one who is praying and finds that his wudu’ is invalidated involuntarily, because urination, defecation and touching do not usually happen when praying. This is similar to the case in which the Prophet (blessings and peace of Allah be upon him) told the one who is not sure whether his wudu’ became invalid whilst he was praying: “One should not stop [praying] unless he hears a sound or notices a smell,” because this is the usual way in which a person’s wudu’ may become invalid whilst praying, and it cannot be imagined that any of the other cases would be applicable in prayer. It is as if he answered the questioner with regard to something of which he was unaware, or with regard to what he needed to know in most cases, or what often happens when praying..