Abbas bin Sahl said: Once Abu Humayd, Abu Usayd, Sahl bin Sa'd and Muhammad bin Maslamah (may Allah be pleased with them) gathered together and mentioned the prayer of the Messenger of Allah (peace and blessings be upon him). Abu Humayd (may Allah be pleased with him) said: "I know more than all of you about the prayer of the Messenger of Allah (peace and blessings be upon him)." In it, it is mentioned that he (peace and blessings be upon him) then sat (after finishing the second prostration), laid down his left foot and kept the front of his right foot facing the qiblah; then he placed his right palm on his right knee and his left palm on his left knee, and pointed with his index finger.
This is about his (peace and blessings be upon him) first tashahhud; there is no mention of the second tashahhud in this hadith.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 2774