[When they entered upon him] in the form of humans, [and said, "Peace."]—meaning: they greeted him. [He said, "Peace,"]—responding to them. ["(You are) a people unknown."]—he did not recognize them because they did not eat from his food.

Muhammad said: ["They said, 'Peace'" (qālan salāman)] is in the accusative case [by implication]: We greet you with a peace (salāman).

And his saying: ["He said, 'Peace'" (qāla salāmun)] is in the nominative case with the meaning: He said, "Peace be upon you (salāmun ʿalaykum)." It is also permissible that it is in the sense of: Our matter is peace.