Addition and omission of the acts and condition of prayers

1272. Whenever a person intentionally adds something to the obligatory acts of prayers, or omits something from them, even if it be only a letter, his prayers become void.

1273. If a person adds or omits the Rukn (elemental parts) of prayers due to ignorance, his prayers are void. But adding or omitting a non-Rukn due to justifiable ignorance or by relying on some authority, will not make the prayers void.
And if someone, due to his ignorance about the rule, prays Fajr, Maghrib and Isha with silent Qir'at, or Zuhr and Asr with loud Qir'at, or offers four Rak'ats where he should have prayed two because of travelling, his prayers will be in order.

1274. If a person realises during prayers that his Wudhu or Ghusl had been void, or that he had begun offering prayers without Wudhu or Ghusl, he should abandon that prayers and repeat the same with Wudhu or Ghusl. And if he realises it after the prayers, he should pray again with Wudhu or Ghusl. And if the time for the prayers has lapsed, he should perform its qadha.

1275. If a person remembers after reaching Ruku, that he has forgotten the two Sajdah of the preceding Rak'at, his prayers are void. And if he remembers before going to Ruku, he should return to perform the two Sajdah. Then he should stand up to recite Surah al-Hamd and Surah or Tasbihat Arba'ah, and complete the prayers. And after the prayers, he should, on the basis of recommended precaution, perform two Sajdatus Sahv for additional standing.

1276. If a person remembers before saying "Assalamu alayna" and "Assalamu Alaykum" that he has not performed the two Sajdah of the last Rak'at, he should perform the two Sajdah and should recite tashahhud again, and then recite Salam.

1277. If a person realises before the Salam of prayers, that he has not offered one Rak'at or something more from the end part of prayers, he should perform the part which had been forgotten.

1278. If a person realises after the Salam of prayers that he has not offered one Rak'at or more from the end part of the prayers, and if he has done any such thing which would invalidate the prayers, were he to do so intentionally or forgetfully, like turning away from Qibla, his prayers will be void.
But if he has not performed any such act then, he should immediately proceed to perform that part of the prayers which he forgot, and should, as an obligatory precaution, offer two Sajdatus Sahv for additional Salam.

1279. If a person after the Salam of prayers, does an act which would have invalidated the prayers, were then to do so intentionally or otherwise, like turning away from Qibla, and then remembers that he had not performed two Sajdah, his prayers will be void.
And if he remembers it before he performs any act which would invalidate the prayers, he should perform the two forgotten Sajdah, and should recite tashahhud again, together with Salam of the prayers. Thereafter, he should perform two Sajdatus Sahv for the Salam recited earlier.

1280. If a person realises that he has offered the prayers before its time set in, he should offer that prayers again, and if the prescribed time for it has lapsed, he should perform its qadha. If he realises that he has offered the prayers with his back to Qibla, he should pray again if the time of namaz is still there, and if the time has lapsed, there will be qadha if he had prayed opposite because of uncertainty about Qibla.
And if he prayed towards the right or the left of Qibla, and realised it after the time of namaz has lapsed, there is no qadha. But if he realises while the time of namaz is still on, he has to pray again, if he had not made enough efforts to determine the direction of Qibla.