1. What is the ruling on repeating the Fajr prayer with another person after I have already led it as the regular Imam in the congregational mosque? 2. What is the ruling on the extra Takbir (saying "Allahu Akbar") for standing up for the fourth Rak'ah in a four-Rak'ah prayer after inadvertently sitting for the third, and does it necessitate Sujud Al-Sahw (prostration of forgetfulness)? 3. How is the method of spitting (exhaling with slight spittle) done after seeking refuge (from Satan) in prayer: Is it by the worshiper turning their head completely, partially, or merely by exhaling with the mouth towards the left?

If your intention for the second prayer is that it is a supererogatory (nafila) prayer, then there is no harm in that, and it is permissible for someone performing a supererogatory prayer to lead someone performing an obligatory (fard) prayer. However, if you intend to repeat the obligatory prayer, it is not permissible, due to the Prophet's ﷺ prohibition of praying the obligatory prayer twice in one day. If a worshiper sits during the third rak'ah out of forgetfulness, he should stand up, perform the fourth rak'ah, recite the tashahhud (definition), and say the taslim (definition), then perform the two prostrations of forgetfulness (sujud (definition) al-sahw). If you wish to seek refuge from Satan during prayer, turn your head slightly to the left and spit three times, based on the hadith (definition) of Uthman ibn Abi al-'As with the Prophet ﷺ.