The wordings for the Tashahhud and the blessings on the Prophet (peace and blessings of Allah be upon him) that have been narrated in reports are many and various.
It is best for the Muslim to recite all of them, saying it in one form on one occasion and in another form on another occasion, and so on, so that he will have done all the sunnahs. He should not limit himself only to some of them. But if that is too hard for him, then he should stick to what he is able to do, and there is no sin on him in sha Allah.
There follow some of the versions of the Tashahhud and blessings on the Prophet (peace and blessings of Allah be upon him) that have been narrated in proven reports from the Prophet (peace and blessings of Allah be upon him) in the prayer.
Ibn Mas’ood (may Allah be pleased with him) recited the Tashahhud as follows: At-tahiyyaatu Lillaahi wa’s-salawaatu wa’t-tayyibaat, as-salaamu ‘alayka ayyuha’n-Nabiyyu wa rahmat-Allahi wa barakaatuhu. As-salaamu ‘alayna wa ‘alaa ‘ibaad-Illaah is-saaliheen. Ash-hadu an laa ilaaha ill-Allah wa ash-hadu anna Muhammadan ‘abduhu wa rasooluhu (All compliments, prayers and pure words are due to Allah. Peace be upon you, O Prophet, and the mercy of Allah and His blessings. Peace be upon us, and on the righteous slaves of Allah. I bear witness that none has the right to be worshipped except Allah, and I bear witness that Muhammad is His slave and Messenger). (Narrated by al-Bukhaari and Muslim).
Ibn ‘Umar (may Allah be pleased with him) recited the Tashahhud as follows: At-tahiyyaatu Lillaahi wa’s-salawaatu wa’t-tayyibaat, as-salaamu ‘alayka ayyuha’n-Nabiyyu wa rahmat-Allahi wa barakaatuhu. As-salaamu ‘alayna wa ‘alaa ‘ibaad-Illaah is-saaliheen. Ash-hadu an laa ilaaha ill-Allah wahdahu laa shareeka lah wa ash-hadu anna Muhammadan ‘abduhu wa rasooluhu (All compliments, prayers and pure words are due to Allah. Peace be upon you, O Prophet, and the mercy of Allah and His blessings. Peace be upon us, and on the righteous slaves of Allah. I bear witness that none has the right to be worshipped except Allah alone with no partner or associate, and I bear witness that Muhammad is His slave and Messenger). (Narrated by Abu Dawood).
The Tashahhud of ‘Umar was recited by him on the minbar in order to teach the people: “At-tahiyyaatu Lillaahi, az-zaakiyaatu Lillaahi, al-tayyibaatu Lillaahi, al-salawaatu Lillaahi. As-salaamu ‘alayka ayyuha’n-Nabiyyu wa rahmat-Allahi wa barakaatuhu. As-salaamu ‘alayna wa ‘alaa ‘ibaad-Illaah is-saaliheen. Ash-hadu an laa ilaaha ill-Allah wa ash-hadu anna Muhammadan ‘abduhu wa rasooluhu (All compliments are due to Allah, all pure things are due to Allah, all pure words are due to Allah, all prayers are due to Allah. Peace be upon you, O Prophet, and the mercy of Allah and His blessings. Peace be upon us, and on the righteous slaves of Allah. I bear witness that none has the right to be worshipped except Allah, and I bear witness that Muhammad is His slave and Messenger). (Narrated by Malik).
As for the wording of the blessings on the Prophet (peace and blessings of Allah be upon him), it is as follows:
“Allahumma salli ‘ala Muhammad wa ‘ala aali Muhammad kama salayta ‘ala Ibraaheem wa ‘ala aali Ibraaheem, innaka hameedun majeed. Allahumma baarik ‘ala Muhammad wa ‘ala aali Muhammad kama baarakta ‘ala Ibraaheem wa ‘ala aali Ibraaheem, innaka hameedun majeed (O Allah, send prayers upon Muhammad and upon the family of Muhammad, as You sent prayers upon Ibraaheem and upon the family of Ibraaheem; You are indeed Worthy of Praise, Full of Glory. O Allah, send blessings upon Muhammad and upon the family of Muhammad as You sent blessings upon Ibraaheem and upon the family of Ibraaheem; You are indeed Worthy of Praise, Full of Glory).” (Narrated by al-Bukhaari).
“Allahumma salli ‘ala Muhammad wa ‘ala aali Muhammad kama salayta ‘ala aali Ibraaheem, wa baarik ‘ala Muhammad wa ‘ala aali Muhammad kama baarakta ‘ala aali Ibraaheem fi’l-aalameen, innaka hameedun majeed (O Allah, send prayers upon Muhammad and the family of Muhammad, and send blessings upon Muhammad and the family of Muhammad, as You sent prayers and blessings upon Ibraaheem and the family of Ibraaheem among the nations; You are indeed Worthy of Praise, Full of Glory).”
It should be noted that the Salam on the Prophet is said right after the Tashahhud.
The rightly guided people are not specific persons but all those servants of Allah who humbly worship him and lead a pious life which they take as a transitory world to sow good deeds in order to collect rewards in the Hereafter.