Sallallaahu 'Alayhi wa Sallam is basically meaning (Allaah Bless Him & Give Him Peace). So can I say "Moosa (Sallallaahu 'Alayhi wa Sallam)" or for any other Messenger or Prophet other than our own beloved Messenger, MuHammad (Sallallaahu 'alayhi wa sallam)? I know it's necessary to be said for our Prophet and he is the greatest of all the Prophets! And so he deserves it the most! But can it be permissible or even praiseworthy for the other messengers as long as people know you're not "requiring" it to be said for those other messengers? I just want to pray for their blessings and peace as well if I mention their specific names. Someone who has a background in traditional Sunni Islaamic education, please answer. No disrespect to anyone else!
Is it permissible to ask for peace & blessings on a messenger other than the Prophet MuHammad (Allaah Bless Him & Give Him Peace)?
Well, as far as I know we do say, for example, Musa alayhee salam which translates to Upon him be peace. Salallahu allayhee wa salam means upon him be the greetings of Allah and peace. (And of course with translation comes some loss of meaning...) This is because we revere and want to venerate all of the prophets, peace be upon them all.
Narrated `Abdur-Rahman bin Abi Laila, saheeh bukhari
Kab bin 'Ujra met me and said, "Shall I give you a present? Once the Prophet came to us and we said, 'O Allah's Apostle ! We know how to greet you; but how to send 'Salat' upon you? He said,
'Say: Allahumma Salli ala Muhammadin wa 'ala Ali Muhammadin, kama sal-laita 'ala all Ibrahima innaka Hamidun Majid. Allahumma barik 'ala Muhammadin wa 'ala all Muhammadin, kama barakta 'ala all Ibrahima, innaka Hamidun Majid."
O Allah! Send your greetings (Salawat) on Muhammad and his family, the same way as You sent Your Salawat on Abraham’s family. O Allah! Send Your blessings on Muhammad and on Muhammad’s family, the same way as You sent Your blessings on Abraham’s family. You are indeed worthy of all praise, full of glory
Saying Salwat is not restricted to the prophet Muhammed (PBUH). Sheikh Ibn Othaymen quote the hadtih in Buhkary as a proof,
Narrated 'Abdullah bin Abu Aufa : Whenever a person came to the Prophet (ﷺ) with his alms, the Prophet (ﷺ) would say, "O Allah! Send your Blessings upon so and so." My father went to the Prophet (ﷺ) with his alms and the Prophet (ﷺ) said, "O Allah! Send your blessings upon the offspring of Abu Aufa."
Another hadith in Sunan Abi Dawud,
Narrated Jabir ibn Abdullah: A woman said to the Prophet (ﷺ): Invoke blessing on me as well as on my husband. The Prophet (ﷺ) said: May Allah send blessing on you and your husband.
Also, in the Quran:
It is He who confers blessing upon you, and His angels [ask Him to do so] that He may bring you out from darknesses into the light. And ever is He, to the believers, Merciful. http://quran.com/33/43
However, there is a difference of opinion regarding saying Salwat on people in general or only prophets and messengers. According to Majority , including Malik and Shafi, we only say salawat on the prophets and not humans. i.e: We don't say alahmu Sali ala Omar, Abu baker. Nevertheless, we are allowed to say salwat on them if we mention the name of messengers/prophets first. i.e: "Allahuma Sali ala Muhamed wa Alihi wa Sahbihi"
The other opinion by Ahmed and some scholars, Salawat can be said to regular Muslims.