The Messenger of Allah( may peace be upon him) used to teach us the tashahhud as he would teach us the Qur’an, and would say: The blessed adoration of the tongue, acts of worship (and) all good things are due to Allah. Peace be upon you, O Prophet, and Allah’s mercy and His blessings. Peace be upon us and upon Allah’s upright servants. I testify that there is no god but Allah, and I testify that Muhammad is Allah’s apostle (peace be upon him).
Sunan Abi Dawud Book 2, Hadith 585
← Previous Hadith When he( the imam) recites the Qur’an, keep silence(and listen attentively). And in the tashahhud this version adds after the words “I testify that there is no god but Allah” the words “He is alone, and there is no associate of Him.”

Abu Dawud said: His word "And keep silence" is not guarded; it has been narrated by Sulaiman al-Taimi alone in his version.

Sunan Abi Dawud Book 2, Hadith 584 Next Hadith → The Messenger of Allah (ﷺ) commanded us (to recite) when we sit in the middle of the prayer or at its end before the salutation: The adorations of the tongue, all good things, acts of worship, and the Kingdom are due to Allah. Then give salutation to the right side; then salute your reciter (i.e. the imam) and yourselves.

Abu Dawud said: Sulaiman b. Musa hails from Kufah and he lives in Damascus.

Abu Dawud said: This collection of traditions indicates that al-Hasan (al-Basri) heard traditions from Samurah (b. Jundub).

Sunan Abi Dawud Book 2, Hadith 586