the first tashahhud, nor do I know of anyone who held this view.
Rather, some hold that one should sit with the buttocks on the ground in both tashahhuds; this is Mālik’s position. Others hold that one should sit on the left foot in both, keeping the right foot upright and laying the left foot flat to sit on it; this is Abū Hanīfah’s view. Others hold that one should sit with the buttocks on the ground in every tashahhud followed by the salām, and sit on the left foot otherwise; this is al-Shāfi‘ī’s view. Others hold that, in every prayer containing two tashahhuds, one should sit with the buttocks on the ground in the latter (1), to distinguish between the two sittings; this is Imām Ahmad’s view (2).
The statement in Ibn al-Zubayr’s hadith that he laid his right foot flat means that, during this sitting, he sat on his buttocks, with his right foot laid flat, his left foot between his thigh and lower leg, and his buttocks on the ground. Thus, the accounts differed concerning his right foot during this sitting: was it laid flat or held upright? Yet this—and Allah knows best—is not really a discrepancy. He did not sit on his foot; rather, he extended it to his right, so that it was neither fully upright nor fully flat, resting on the right side of its sole. It was flat in the sense that he was not holding it upright while sitting on his heel, and upright in the sense that he was not sitting on its sole with its upper surface against the ground. Thus, both the account of Abū Humayd and those with him and that of ‘Abd Allāh ibn al-Zubayr are correct. Alternatively, it may be said that he (peace and blessings be upon him) practised both: he would hold his foot upright, but sometimes laid it flat, which was more comfortable for it. And Allah knows best.
Then he (peace and blessings be upon him) would always recite the tashahhud in this sitting, and teach his Companions to say: