It is narrated from Abdullah bin Mas'ud (may Allah be pleased with him) that he said: "The Messenger of Allah (ﷺ) used to sit (for Tashahhud) after the first two rak'ahs as if he were sitting on a hot stone." Imam Shafi'i said: "Until he would stand up?" Ibrahim (may Allah have mercy on him) said: "Yes! That is what he intended to convey."
Hadith Referenceمسند الإمام الشافعي / كتاب الصلاة / 251
Hadith Takhrijاسنادہ ضعیف لانقطاعه فإن أبا عبیدۃ لم یسمع من أبیه، أخرجہ أبو داود، الصلاۃ، باب فی تخفیف القعود: 995 - والترمذی، الصلاۃ، باب ما جاء فی مقدار القعود فی الرکعتین الأولین: 366 - وقال حسن إلا أن أبا عبیدۃ لم یسمع من أبیه۔
It is narrated from Abu Humayd As-Sa'idi (may Allah be pleased with him) that he said: "When the Messenger of Allah (ﷺ) sat after two rak'ahs, he would spread his left foot and sit on it, and keep his right foot upright. And when he sat after four rak'ahs, he would move his feet away from his buttocks and sit on the ground with his buttocks, and place his right buttock on the ground."
Hadith Referenceمسند الإمام الشافعي / كتاب الصلاة / 252
Hadith Takhrijاسنادہ ضعیف لکن الحدیث صحیح من غیر ہذا الطریق أخرجہ أبو داود، الصلاۃ، باب افتتاح الصلوۃ: 734، 735 - والترمذی، الصلاۃ، باب ما جاء أنه یجافی یدیه عن جنبه فی الرکوع: 260 - وقال حسن صحیح وصححه ابن خزیمة 589، 608، 638، 689۔
It is narrated from Ali bin Abdur Rahman Al-Mu'awi, he states: "Ibn Umar (may Allah be pleased with them both) saw me playing with pebbles. When he finished the prayer, he forbade me and said: Do as the Messenger of Allah (ﷺ) used to do." Ali bin Abdur Rahman says, I asked: "How did the Messenger of Allah (ﷺ) do?" Ibn Umar (may Allah be pleased with them both) replied: "When the Prophet (ﷺ) sat in prayer (for Tashahhud), he would place his right palm on his right thigh, then close all his fingers and point with the finger next to the thumb (the index finger), and place his left palm on his left thigh."
Hadith Referenceمسند الإمام الشافعي / كتاب الصلاة / 253
Hadith Takhrijأخرجہ مسلم، المساجد، باب صفة الجلوس في الصلوة، وكيفية وضع اليدين على الفخذين: 580۔