Two people related by Faith should use the expression of peace and security to address each other. Thus Islam taught Muslims to say Assalamu Alaikum (Peace be upon you), and replaced all other formulas of greeting.
In this small greeting is hidden an excellent and comprehensive prayer, kindness and affection for the young, and respect and attention for the elders.
Almighty Allah employs the same greeting in the Glorious Quraan to address His beloved Prophets as a mark of His favour and esteem on them. "Peace be unto Nuh among the people" (37:79); "Peace be unto Ibrahim" (37:109) "Peace be unto Musa and Harun" (37:120); "Peace be unto Ilyas" (37:130); "Peace be unto those sent (to warn)" (37:59); and "Peace be on His slaves whom He hath chosen" (27:59). Believers will also be welcomed into Paradise with the same expression: "Enter them in Peace" (15:46) and "Peace be unto you because you preserved. Ah, passing sweet will be the sequel of the (heavenly) home" (13:24).
Salaam is a distinctive practice of Islam and Muslims have been recommended to make common the greeting. The Messenger of Allah, Sallallaho Alayhi Wasallam, said: "Oh people! Worship Allah, The Beneficent, feed His bondsmen, and spread Salaam much, and you will reach Heaven in safety." (Tirmidhi)
Divine reward for the blessed act of performing Salaam is explained in a Hadith. Once a person came to the Prophet, Sallallaho Alayhi Wasallam, and said: "Assalaamu Alaikum." The Prophet, Sallallaho Alayhi Wasallam, returned the greeting, and when the man had sat down, he said: "Ten good deeds have been written in his name owing to this Salaam." Thereafter another person came and said: "Assalaamu Alaikum Warahmatullahi" (Peace be with you, and the mercy of Allah). The Prophet, Sallallaho Alayhi Wasallam, returned the greeting, and when the man had sat down, he said: "Twenty good deeds have been written in his name." Then, another man came and said: "Assalaamu Alaikum Warahmatullahi Wa Barakatuh" (Peace be with you, and the mercy of Allah, and His blessings). The Prophet, Sallallaho Alayhi Wasallam, returned the greeting, and when the man had sat down, he said: "Thirty good deeds have been written in his name." (Tirmidhi and Abu Dawood)
Such was the value of Salaam in the early Muslims that it is related Hadhrat Abdullah bin Umar, Radhiyallo Anhu, would go to the market solely for the purpose of making greeting to whoever he saw.
Salaam has a deep spiritual side besides signifying the sentiments of joy, regard and well-wishing. The Messenger of Allah, Sallallaho Alayhi Wasallam, said: "He who is the first to greet is free from pride." (Baihaqi) Therefore to take precedence in making the greeting is a sign of freedom from vanity. It can also mean it is a cure for the grave sin of pride.
The importance of Salaam is further emphasized by the Prophet, Sallallaho Alayhi Wasallam, who advised that Salaam should be exchanged a second time if after meeting a Muslim, even for a brief moment, they are separated by a tree, wall, or rock, and they meet again.
Salaam should be said when entering or leaving one's home. A Hadith informs us that this is a source of blessing to the person saying it as well to the family members. Similarly, the person arriving at a congregation should be the first to greet those who are present; the young are instructed to take the lead in greeting the elders; those passing should greet those sitting; and men of a smaller group should greet men of the larger group.
To shake the hand simultaneously with greeting marks the fulfillment of the aim and object of Salaam. The Messenger of Allah, Sallallaho Alayhi Wasallam, said: "Shaking hands denotes the completion of greeting." (Tirmidhi and Abu Dawood)
Salaam is in essence a really wonderful teaching of Islam. It not only increases love and affection between Muslims but is also a cause of their forgiveness. The Prophet of Allah, Sallallaho Alayhi Wasallam, said: "When two Muslims meet and shake hands, and at the same time glorify the Allah, and beg forgiveness for themselves, they will be forgiven." (Abu Dawood)
The Salaam Poem
