Sequence.

1130. If a person intentionally changes the sequence of the prayers, for example, if he recites the other Surah before reciting Surah al-Hamd, or performs Sajdah before Ruku, his prayers are void.

1131. If a person forgets a Rukn (elemental part) of the prayers, and performs the next Rukn, like before performing Ruku if he performs the two Sajdah, his prayers would become void.

1132. If a person forgets a Rukn, and performs an act after it which is not a Rukn, like if he recites Tashahhud without performing the two Sajdahs, he should perform the Rukn and should recite again the part which he performed erroneously, earlier than the Rukn, and, as an obligatory precaution, he must perform two Sahv Sajdahs for each addition.

1133. If a person forgets a thing which is not a Rukn, and performs a Rukn which comes after it, like if he forgets Surah al-Hamd and begins performing Ruku, his prayers is in order; and, as an obligatory precaution, he must perform two Sahv Sajdahs.

1134. If a person forgets an act which is not a Rukn, and performs the next act which too is not a Rukn, like if he forgets Surah al-Hamd and recites the other Surah, if he has started the next Rukn and then while performing Ruku he remembers that he has forgotten to recite Surah al-Hamd, he must ignore it and his Namaz is in order and for every obligatory act which is forgotten, he must perform two Sahv Sajdah as an obligatory precaution; and if he has not started the next Rukn, he must perform what he has forgotten, and then recite again the thing which he mistakenly recited earlier and, as an obligatory precaution, he must perform two Sahv Sajdahs for any addition.

1135. If a person performs the first Sajdah thinking that it is the second one or performs the second one under the impression that it is the first Sajdah, his prayer is in order; his first Sajdah will be treated as the first one, and his second Sajdah will be treated as the second one.