When was the Tashahhud legislated in prayer, what does it mean, or how was it related by the Prophet Muhammad, may God’s prayers and peace be upon him?

The good among deeds, sayings, and actions is offered to the good. "Assalamu alayka" (Peace be upon you) It was said that "Salam" (Peace) is one of the names of Allah Almighty, and its meaning is Allah's preservation and care for the Messenger (peace be upon him). It was also said that "Salam" is a verbal noun meaning saluting the Messenger and supplicating for his safety from all harm. "Wa rahmatullahi" (And the mercy of Allah) When mercy is coupled with forgiveness or peace, its meaning is that by which what is desired is attained, while forgiveness and peace are what remove what is feared. "Wa barakatuhu" (And His blessings) is the plural of "barakah" (blessing), meaning abundant and enduring good. "Assalamu alayna" (Peace be upon us) means peace upon the Muhammadan Ummah. "Wa ala ibadillahis-salihin" (And upon the righteous servants of Allah) is a generalization after specification, meaning every righteous servant in the heavens and the earth, whether alive or dead, from among humans, angels, and jinn, whose inner and outer selves have been rectified. "Ashhadu an la ilaha illallah" (I bear witness that there is no god but Allah) is the word of monotheism with which all messengers were sent, and "wa ashhadu anna Muhammadan abduhu wa rasuluhu" (and I bear witness that Muhammad is His servant and His Messenger) means that Muhammad is a worshipper of Allah and has no share in Allah's dominion; he is a human being distinguished by revelation, and "His Messenger" means Allah sent him to convey His law, and he is the Seal of the Prophets and Messengers and the best of them.