Ibn Abbas, that this invalidates the prayer. Mujahid and Ishaq granted an exemption for the elderly person. Our position is that this has not been reported from the Prophet (peace and blessings of Allah be upon him), and Ibn Abbas disliked it. Furthermore, it is possible for an elderly person to lean on his hands, thus rendering it unnecessary. The prayer is not invalidated by it, because it is not a large amount of movement, nor is there anything in it that necessitates invalidation.
Section: Then he prays the third and fourth rak'ahs like the second, except that he does not recite anything in them after the Fatiha, nor does he recite aloud in them in a prayer where recitation is loud. The explanation of that will follow, if Allah the Almighty wills.
176 - Issue: He said: (Then when he sits for the final tashahhud, he performs tawarruk, setting his right foot upright, placing the bottom of his left foot beneath his right thigh, and placing his buttocks upon the ground).
The Sunnah, according to our Imam (may Allah have mercy on him), is the tawarruk in the second tashahhud. Malik and al-Shafi'i held this view as well. Al-Thawri and the People of Opinion (Ashab al-Ra'y) said: He sits in the iftirash position just as he sits in the first, due to what we have mentioned from the hadith of Wa'il ibn Hujr and Abu Humayd regarding the description of the Prophet's (peace and blessings of Allah be upon him) sitting. Our argument is the statement of Abu Humayd: 'Until, when it was the rak'ah in which he completes his prayer, he pushed his left foot backward and sat in the tawarruk position on his left side.' This is a clarification of the difference between the two tashahhud sittings, and an addition which must be adopted and adhered to. The evidence they used concerning the first tashahhud is not in dispute between us, and Abu Humayd, the narrator of their hadith, clarified in his hadith that his iftirash was in the first tashahhud and that he performed tawarruk in the second. Thus, it is mandatory to adopt his statement and explanation.
As for the description of the tawarruk, al-Khiraqi said: He sets his right foot upright, places the bottom of his left foot beneath his right thigh, and places his buttocks on the ground. Al-Qadi mentioned the same, due to what was narrated from Abdullah ibn al-Zubayr who said: When the Messenger of Allah (peace and blessings of Allah be upon him) sat in prayer, he placed...
(1) In the original: "the elder". (2) In the original: "like the second". (1) Omitted from M.