The eminent Muslim scholar and renowned Da`iyah, Sheikh `Abdel Khaliq Hasan Ash-Shareef, states: “Acts like Tawaf, Sa`y, and others, which are related to the category of `Ibadaat, are orders of Allah the Almighty. The scholars have classified them as Ta`budi acts, which means that we cannot pinpoint one particular reason in the sense that if that reason is not there we can dispense with the act. This cannot be done in case of Ta`bud; they are rituals that we must fulfill regardless whether their immediate benefits are clear or not. We apply such acts as Almighty Allah commands us. Similarly, we cannot ask why Zuhr prayer is four rak`as and maghrib is four rak`as, etc.
Furthermore, there is no particular numbers for the rituals of Islam. Maghrib prayer consists of three Rakh`as, `Ishaa’ prayer consists of four rak`as, Fajr prayer consists of two rak`as, etc.
As for the issue of cleaning a bowl touched by a dog, there is a hadith telling that it should be washed three times and another hadith telling that it should be washed seven times.
Thus, what is important to be clear with is that there is no particularity for a certain number in Islam.”