Sayyiduna Ibn Mas'ud (may Allah be pleased with him) narrates that when we used to sit in Tashahhud with the Prophet (peace and blessings be upon him), we would say: "Peace be upon Allah from His servants." When the Prophet (peace and blessings be upon him) heard us saying this, he said: "Allah Himself is the embodiment of peace, so instead of saying this, say: «التَّحِيَّاتُلِلّٰهِوَالصَّلَوَاتُوَالطَّيِّبَاتُالسَّلَامُعَلَيْكَأَيُّهَاالنَّبِيُّوَرَحْمَةُاللّٰهِوَبَرَكَاتُهُالسَّلَامُعَلَيْنَاوَعَلَىعِبَادِاللّٰهِالصَّالِحِينَأَشْهَدُأَنْلَاإِلٰهَإِلَّااللّٰهُوَأَشْهَدُأَنَّمُحَمَّدًاعَبْدُهُوَرَسُولُهُ» 'All verbal, physical, and bodily acts of worship are for Allah alone. O Prophet (peace and blessings be upon him), may Allah's peace, mercy, and blessings descend upon you. May peace descend upon us and upon the righteous servants of Allah. I bear witness that there is no deity except Allah and that Muhammad (peace and blessings be upon him) is Allah's servant and His Messenger.'"
Hadith Referenceمسند احمد / مسند المكثرين من الصحابة / 4422