مسائل المنتخبه (Articles Of Islamic Acts) - الخوئي، السيد أبوالقاسم - الصفحة ٢٤٠ - SALAM (SALUTATION) OF THE PRAYERS

Assalamu alaykum. And it is recommended that he should add wa rahmatullahi wa barakatuh after Assalmu alaykum and should recite both the salams.
١١١٥. If a person forgets the salam of prayers and recollects this when the shape of the prayers has not yet been upset, and has also not performed any act, which,if done intentionally or by mistake, nullifies the prayers (e.g. turning from qibla) he should recite the salam and his prayers is in order.
١١١٦. If a person forgets the salam of prayers and recollects this when the shape of the prayers has been upset, or he has performed an act, which, if doneintentionally or by mistake. nullifies the prayers (e.g~ turning back from Qibla) his prayers is in order.
 TARTIB (SEQUENCE)
TARTIB (SEQUENCE)
١١١٧. If a person intentionally changes the sequence of the component acts of the prayers, for example, if he recites the other surah before reciting Surah al-Hamdor performs the two prostrations before performing bowing, his prayers is void.
١١١٨. If a person forgets a rukn (basic element) of the prayers and performs the succeeding rukn, for example before performing bowing he performs the two sajdas,his prayers would become void.
١١١٩. If a person forgets a rukn and performs an act which comes after it and is not a rukn, for example if he recites tashahhud before performing the twoprostrations he should perform the rukn and should recite again the thing which he recited earlier than the Rukn by mistake.
١١٢٠. If a person forgets a thing which is not a rukn and performs s rukn which comes after it, for example if he forgets Surah al-Hamd and begins performing bowinghis prayers is in order.
١١٢١. If a person forgets a thing which is not a rukn and