When Abu Humaid described the prayer of the Prophet, upon whom be peace, he said, “When he sat after two rak’ah, he would sit upon his left leg and keep his right foot upright. When he sat for the last rak’ah, he would pull over his left foot and put his right foot upright (over the left foot) and sit upon his entire posterior.” (Related by al-Bukhari.)
Most scholars say that the first tashahud is sunnah
This is based on the hadith of ‘Abdullah ibn Buhainah who reported that once the Prophet stood during the noon prayer when he should have sat (for the first tashahud). When he finished the prayer, he made two prostrations. He made a takbir for each prostration (and it was) while he was sitting before he made the tasleem. He made those two prostrations because he had forgotten to sit (for the first tashahud). (Related by “the group.”)
In Subul as-Salaam, it is stated that this hadith proves that one who forgets the first tashah ud must make the prostrations of forgetfulness. The Prophet is, however, reported to have said, “Pray as you have seen me pray.” This would point to the first tashahud being obligatory, and one would have to do some act to make up for it. But, this also proves that it is not obligatory, for if one misses an act that is obligatory, the two prostrations of forgetfulness are not sufficient to make up for it. That is what Ibn Hajr says in Fath al-Bari.
Says Ibn Batal, “The proof is that the two prostrations due to forgetfulness cannot replace something that is obligatory. If one forgets the opening takbir, they will not replace it. In the case of the tashahud, it is a remembrance that is not said aloud and it is not obligatory.” Some say otherwise, because the Prophet used to perform it and, as such, he let others follow him in performing it after he found out that they were leaving it intentionally. But there is some doubt about this argument. Those who say that it is obligatory include al-Laith Ibn Sa’d, Ishaq, ash-Shaf’i and the Hanafiyyah. At-Tabari argues that it is obligatory because originally only two rak’ah and the tashahud were obligatory. When they were made longer, the original obligations were not done away with. Therefore, it is still obligatory.
It is preferred to make the first tashahud quickly
Reported Ibn Mas’ud, “When the Prophet sat after the first two rak’ah, it seemed as if he was (sitting) on hot stones.” This is related by Ahmad, Abu Dawud, an-Nasa’i, at-Tirmizhi and Ibn Majah. At-Tirmizhi grades it as hassan and says, ‘Ubaidah (ibn ‘Abdullah ibn Mas’ud) did not hear (hadith) from his father. He also says, “The scholars act according to this hadith. They prefer that one should not sit too long after the first two rak’ah, and that he should not add anything to the tashahud.”
Says Ibn al-Qayyim, “It is not reported from the Prophet that he would say prayers upon himself or his family during the first tashahud. Nor would he seek refuge from the torment of the grave or the Hell-fire, or from the test of life, death and of the false Messiah. Those who say such supplications are deducing their arguments from the general application (of the supplications and the word tashahud), but the correct position is that their proper place is in the last tashahud.