Salutations on the Holy Prophet-saww and his-saww Pure Progeny-asws
The word Salawāt ‘صَلَوَات’ means reverence or Salutations, it is mentioned in, at least, three places in the Holy Quran Allah-azwj and His angels Send Salawāt upon Prophet-saww and his-saww pure and pious progeny-asws, and those with the Eman (believers) are asked to follow suit.
(1) Surely, Allah and His Angels are Sending Salawāt upon the Prophet. O you those who believe! Send Salawāt upon him and submit submissively [33:56],
(2) Those, upon them is the Salawāt from their Lord and Mercy; those, they are the Guided ones [2:157],
(3) He is the One Who Sends Salawāt upon you and (so do) His Angels, in order to Extract you (Momineen) from the multiple darkness to the Light, and He was always Merciful to the Momineen [33:43]
Also, in a Hadith,
معاني الأخبار أَحْمَدُ بْنُ مُحَمَّدِ بْنِ عَبْدِ الرَّحْمَنِ الْمُقْرِي عَنْ مُحَمَّدِ بْنِ جَعْفَرٍ الْمُقْرِي عَنْ مُحَمَّدِ بْنِ الْحَسَنِ الْمَوْصِلِيِّ عَنْ مُحَمَّدِ بْنِ عَاصِمٍ الطَّرِيفِيِّ عَنْ عَيَّاشِ بْنِ يَزِيدَ بْنِ الْحَسَنِ عَنْ أَبِيهِ عَنْ مُوسَى بْنِ جَعْفَرٍ عَنْ أَبِيهِ ع قَالَ: مَنْ صَلَّى عَلَى النَّبِيِّ ص فَمَعْنَاهُ أَنِّي أَنَا عَلَى الْمِيثَاقِ وَ الْوَفَاءِ الَّذِي قَبِلْتُ حِينَ قَوْلِهِ أَ لَسْتُ بِرَبِّكُمْ قالُوا بَلى
(The book) ‘Ma’any Al Akhbar’ – Ahmad Bin Muhammad Bin Abdul Rahman Al Muqry, from Muhammad Bin Ja’far Al Muqry, from Muhammad Bin Al-Hassan Al Mowsily, from Muhammad Bin Aasim Al Tareyfi, from Ayyash Bin Yazeed Bin Al-Hassan, from his father,
From Musa-asws Bin Ja’far-asws, from his-asws father-asws: ‘One who sends Salawaat upon the Prophet-saww, it’s meaning is, ‘I am upon the Covenant and the loyalty which I accepted, when it was His-azwj Words: “Am I not your Lord?” They said, ‘Yes, we testify’. [7:172]’’.[1]
Without recitation of the Salawāt, neither acts of worships are accepted nor one’s prayers, Salawāt obliterates grave sins and removes the hyprocrisy. The apparent meanings of Salawāt are submission to Rasool Allah-saww (and his-saww successors) in whatsoever that is referred to him-saww (Ahadith) whereas its hidden meanings are submit to Prophet-saww’s successor-asws and preferred him-asws over you (Ahadith references to follow).
There are several versions of Salawāt as we find in the Ahadith of Ahl Al-Bayt-asws, for example: اللَّهُمَّ صَلِّ عَلَى مُحَمَّدٍ وَ آلِ مُحَمَّدٍ وَ عَجِّلْ فَرَجَهُمْ, as in a Hadith, below:
الْمُتَهَجِّدُ، وَ الْجُنَّةُ، جُنَّةُ الْأَمَانِ عَنِ الصَّادِقِ ع مَنْ قَالَ بَعْدَ صَلَاةِ الظُّهْرِ وَ صَلَاةِ الْفَجْرِ فِي الْجُمُعَةِ وَ غَيْرِهَا- –
(The books) ‘Al Mutahajjid’, and ‘Al Junnat Al Amaan’ –
From Al-Sadiq-asws: ‘One who says after Al-Zohr Salat and Al-Fajr Salat during the Friday and other (days),
اللَّهُمَّ صَلِّ عَلَى مُحَمَّدٍ وَ آلِ مُحَمَّدٍ وَ عَجِّلْ فَرَجَهُمْ
‘O Allah-azwj! Send Salawaat upon Muhammad-saww and Progeny-asws of Muhammad-saww, and Hasten their-asws relief’
لَمْ يَمُتْ حَتَّى يُدْرِكَ الْقَائِمَ الْمَهْدِيَّ ع
‘He will not die until he comes across Al-Qaim Al-Mahdi-ajfj’’.[2]
NB: https://hubeali.com/salawat-its-meanings-blessings-and-versions/
[1] Bihar Al-Anwaar V 90 – The Book of Zikr (Chapters on supplication) – Ch 29 H 25
[2] Bihar Al-Anwaar V 86 – The Book Salat – Ch 97 H 51