The word nafs (self) may also be used for someone who is unfamiliar to you, as in His statement, “A Messenger has certainly come to you from among your own selves” (Qur’an 9:128). Likewise, His words, “Do not defame yourselves” (Qur’an 49:11) mean: let none of you belittle another; it is not implying that a person would disparage himself.

Accordingly, whenever you enter a house, greet those inside by saying, “Peace be upon you.” They are then obliged to return the greeting. It has already been mentioned that the Sunnah, when you enter your own home, is first to use the siwak and then to extend the greeting of peace to the household.

Allah the Exalted says: “When you are greeted with a salutation, respond with one that is better than it, or return it in kind; surely Allah is ever an Accountant over all things” (Qur’an 4:86). Thus He commands that, when we are greeted, we must either reply with something better or at least equal to it.

For example, if someone says, “Peace be upon you (as-salāmu ʿalayk),” you should reply, “Upon you be peace (ʿalayk as-salām),” without omitting anything. If he says, “Peace be upon you and the mercy of Allah,” reply, “Upon you be peace and the mercy of Allah.” If he says, “Peace be upon you and the mercy of Allah and His blessings,” then you must reply, “Upon you be peace and the mercy of Allah and His blessings.” This is obligatory, because Allah has said, “or return it.”

However, if he says only, “Peace be upon you,” and you reply, “Upon you be peace and the mercy of Allah,” that is better and more excellent, though not obligatory. What is obligatory is to respond with at least the same greeting with which he addressed you.