It is narrated from Ibn Abbas (may Allah be pleased with them both) that he said: The Messenger of Allah (ﷺ) used to teach us the Tashahhud just as he used to teach us the Qur'an, and he (ﷺ) would say: "All blessed words, physical acts, and wealth are for Allah. O Prophet (ﷺ)! Peace be upon you, and the mercy of Allah and His blessings. Peace be upon us and upon the righteous servants of Allah. I bear witness that there is no deity except Allah, and I bear witness that Muhammad (ﷺ) is the Messenger of Allah."
Hadith Referenceمسند الإمام الشافعي / كتاب الصلاة / 254
Hadith Takhrijأخرجہ مسلم، الصلاۃ، باب التشہد فی الصلاۃ: 403۔
It is narrated from Abdur Rahman bin Abdu Qari that he heard Umar bin Khattab (may Allah be pleased with him) teaching people the Tashahhud from the pulpit. He was saying: "You should recite: All verbal, financial, and physical acts of worship are for Allah. O Prophet! Peace be upon you, and the mercy and blessings of Allah. And peace be upon us and upon the righteous servants of Allah. I bear witness that there is no deity except Allah, and I bear witness that Muhammad (ﷺ) is His servant and Messenger."
Hadith Referenceمسند الإمام الشافعي / كتاب الصلاة / 255
Hadith Takhrijاخرجه البيهقي : 144/2، 145 وفى المعرفة السنن والآثار له (890) وعبد الرزاق: 3067 ، 3068 ، 3069 و ابن ابی شیبة: 2992 - وصححه الحاكم: (1/ 266)۔
Ata (may Allah have mercy on him) says: I heard Ibn Abbas and Ibn Zubair (may Allah be pleased with them) and they did not differ in the Tashahhud. (That is, both narrated the same words from the Prophet ﷺ.)
Hadith Referenceمسند الإمام الشافعي / كتاب الصلاة / 256