[Commentary]
The author—may Allah have mercy on him—opens his Riyad al-Salihin with “The Book of the Greeting of Peace.” By the greeting (salam) he intends the salutation that the Prophet, peace and blessings be upon him, prescribed for his ummah. In essence, salam is a prayer that the one addressed be kept safe from every calamity. When you say to someone, “as-salamu ʿalayk” (“peace be upon you”), you are asking Allah to protect him from every harm: from sickness and madness, from the malice of other people, from sins and the diseases of the heart, and from the Fire itself. The phrase is therefore all-embracing; its meaning is a supplication that the person greeted be secure from every affliction.
Out of their love for Allah—Glorified and Exalted is He—the Companions, may Allah be pleased with them, would sometimes say in their prayer, “Peace be upon Allah, peace be upon Gabriel, peace be upon so-and-so and so-and-so.” The Prophet, peace and blessings be upon him, forbade them from saying, “Peace be upon Allah” or “Peace be upon His servants,” and explained, “Allah is as-Salam,” meaning He is free from every defect and imperfection. Hence there is no need to laud Him with a prayer that He grant safety to Himself. Instead, he instructed them to say, “Peace be upon us and upon the righteous servants of Allah,” for when you utter this formula you have extended the greeting to every righteous servant in heaven and on earth.