HiAvok, A simple answer is that the "un" indicate an indefinite noun. salamun= peace; as-salam= the peace. There's no big difference in the meaning in both cases. And salamun alaykum is mentioned in the Qur'an several times, as well as as-salam. So they're both correct. Heshould stand in front of the grave of the Prophet (peace and blessings of Allah be upon him), facing the grave and with his back towards the qiblah, and say, "Al-salamu 'alayka ayyuha'l-Nabiyyu wa rahmat-Allahi wa barakatuhu (Peace be upon you, O Prophet, and the mercy and blessings of Allah).". If he wants to add something Thereare other salutations in Persian greeting, including Salaam Aleykom سلام علیکم (Peace be unto you), Salam o sad salam سلام و صد سلام (hello and one hundred hellos) and Salam be ro-ye mahet سلام به روی ماهت "Hello to your face which is as beautiful as the moon!". Another way to offer greetings is to say Youcan greet each someone in Islam by saying "As-salamu Alaikum wa Rahmatullahi Wa Barakatuh" السلام عليكم ورحمة الله وبركاته" ", which means:" May the peace, mercy, and blessings of Allah be with you". Muslims also say Islamic greetings at the end of praying. It is called "Taslim", the last pillar of AlNawawi (may Allaah have mercy on him) said in his commentary on sahih muslim (14/144-145): The scholars agree that the greeting of the People of the Book should be returned, if they greet us with salaam, but we should not say to them, "Wa 'alaykum al-salaam (and upon you be peace).". We should say only " 'alaykum (upon you)" or Salaammeans 'Peace'. it also can be used as a greeting, used synonymously with 'Assalaamu Alaikum', meaning 'Peace be with you' well salaam means many things and one of them is that when you say UE4SBQ.

is it ok to say salam alaikum