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1173. The following doubts will invalidate the prayer:
1. The doubt concerning the number of rak‘ah, that arises in a two rak‘ah obligatory prayer, such as the fajr prayer, or the traveler’s prayer. However, the doubt with respect to the number of rak‘ah that arises in recommended prayers or the iÎtiyÁÔ prayer does not invalidate it.
2. The doubt concerning the number of rak‘ah, that arises in a three rak‘ah prayer.
3. When a person engaged in a four rak‘ah prayer, doubts whether he has performed one rak‘ah or more.
4. When a person offering a four rak‘ah prayer, doubts prior to completing the dhikr of the second sujÙd whether he has performed two rak‘ah or more.
5. When a person does not know how many rak‘ah he has performed.
6. The doubt between two and five rak‘ah or two and more than five rak‘ah. However, obligatory precaution dictates that when such a doubt arises, one should assume he has offered two rak‘ah, complete his prayer and then repeat it.
7. The doubt between three and six rak‘ah or three and more than six rak‘ah. However, obligatory precaution dictates that when such a doubt arises, one should assume he has offered three rak‘ah, complete his prayer and then repeat it.
8. The doubt between four and six rak‘ah or four and more than six rak‘ah. However, obligatory precaution dictates that when such a doubt arises, one should assume he has offered four rak‘ah, complete his prayer and then repeat it.

1174. If one of the doubts that invalidate prayer arises, one should cogitate to such an extent that the doubt becomes concrete, after which he can break his prayer. It is better to prolong his cogitation until the form of the prayer breaks.