مسائل المنتخبه (Articles Of Islamic Acts) - الخوئي، السيد أبوالقاسم - الصفحة ٢٦٧ - METHOD OF OFFERING PRECAUTIONARY PRAYERS (SALTATUL IHTIYAT)

tashahhud and salaam of the prayers after two prostrations. In case, however, it is obligatory for him to perform ٢ units of "Precautionary Prayers" he should perform, after the ٢ prostrations, another unit like the first one and then recite tashahhud and salaam.
١٢٢٥. "Precautionary prayers" does not require surah and qunut; it should be offered in a low voice; its intention should not be uttered; and the obligatoryprecaution is that its "Bismillah" should also be pronounced in a low voice.
١٢٢٦. If a person realizes before offering "Precautionary Prayers" that the prayers which he offered was correct he need not offer "Precautionary Prayers" and if herealizes this while he is offering "Precautionary Prayers" he need not complete it.
١٢٢٧. If a person realizes before offering "Precautionary prayers" that he offered lesser units of the original prayers and if he has not performed an act, which mayinvalidate prayers. he should recite that part of the prayers which he has not recited and should perform ٢ sajdatus sahu for unnecessary salaam. And if he has performed anyact which invalidates prayers (for example, if he has turned his back towards Qibla) he should reoffer the prayers.
١٢٢٨. If a person realizes after "Precautionary Prayers" that the shortage in his original prayers was equal to the "Precautionary Prayers" for example, if heoffers ١ unit of "Precautionary prayers" in the case of doubt about ٣ and ٤ units, and it transpires later that he had offered ٣ units of the original prayers, his prayers isin order.
١٢٢٩. If a person learns after offering "Precautionary Prayers" that the shortage in the original prayers was lesser than the "Precautionary Prayers" - for exampleif he offers ٢ units of "Precautionary Prayers" in connection with doubt about ٢ and ٤ units and learns later that he had offered ٣ units of prayers he should offer hisoriginal prayers again.