Bismillaah Al-Hamdulillaah wa salatu wa salaamu 'ala rasulullaah
Warning Against The Greeting: 'Sabaahul Khayr', 'Sabaahun Noor', 'Masaa ul-Khayr', 'Masaa-in-Noor'
In The Name of Allaah, The Most Merciful The Bestower of Mercy
A great number of the people would say when they greet one another; "Sabaahul-Khayr or Masaa-ul Khayr!" Their response to this greeting is: "Sabaahun Noor and Masaa-in Noor." This greeting is a Magian greeting (i.e. a greeting of the fire worshippers).
The Magians believe in two powerful (forces): The forces of Good and Evil, which they compare to Light and Darkness. The Magians [deviantly believe in] two gods: The god of goodness or light and the god of evil or darkness, and that these two (gods) contend with one another to rule the world. So this is the reason the Magians greet one another with their statement: Sabaahul Khayr-Sabaahun-Noor, whilst Islaam has commanded us (Muslims) to greet with the Islaamic Greeting "As-Salaamu-Alaykum."
Source: Mu'jamul Manaahiyy Lil-laf-dhiyyah (pgs: 334-335) of Shaikh Bakr Abu Zaid (rahimahullaah)
Proofs from Revelation for the Legislation of the Islaamic Greeting of 'As-salaamu 'alaykum'
The Messenger of Allaah (sallallahu 'alayhi wa sallam) said: When you meet your Muslim brother, give him the salaam. [Bukhaaree, Muslim]
The Messenger of Allaah (sallahu 'alayhi wa sallam) said: Should I not inform you of something that, if you were to do it, would cause you to love one another? Spread the salaam between yourselves. [Muslim]
It is related by Abu Dawud and Al-Tirmidhee, who graded it as Hadith Hasan (good Hadith), on the authority of 'Imran (radiallaahu 'anhu) that he narrated: A man came to the Prophet (salallaahu 'alayhi wa sallam) and greeted him saying, "Al-Salamu 'Alaikum (peace be upon you)," and he replied to him. When the man sat down, the Prophet (peace be upon him) said, "Ten (good deeds)." Another man came and greeted him saying, "Al-Salamu 'Alaikum wa Rahmatullahi", and the Prophet (Peace and Mercy be upon him) replied. When the man sat down, the Prophet (peace be upon him) said, "Twenty." A third man came and greeted him saying, "Al-Salamu 'Alaikum wa Rahmatullahi wa Barakatuh (Peace, Mercy and Blessings of Allah be upon you)", and the Prophet replied. When the man sat down, the Prophet (salallaahu 'alayhi wa sallam) said, "Thirty."
Allaah said (what means): When you are greeted with a greeting, greet in return with what is better than it, or (at least) return it equally. Certainly, Allaah is Ever a Careful Account Taker of all things. (An-Nisa`, ayah 86)
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