Ibn Abbas, may Allah be pleased with him, said: By “people” He meant those who believed in Mecca: Salamah ibn Hisham, Ayyash ibn Rabi'ah, al-Walid ibn al-Walid, Ammar ibn Yasir, and others. Ibn Jurayj said: It was revealed concerning Ammar ibn Yasir, who was being tortured for the sake of Allah (1).
Muqatil said: It was revealed concerning Mihja' ibn Abd Allah, the freedman of Umar. He was the first Muslim to be killed on the day of Badr. The Prophet, peace and blessings be upon him, said: “Mihja' is the leader of the martyrs, and he is the first member of this community who will be called to the gate of Paradise.” His parents and his wife were overcome with grief, so Allah revealed this verse concerning them (2).
It was also said that the meaning of “and will not be tested” is: tested through commands and prohibitions. This is because Allah Most High initially commanded them only to believe; then He made prayer, zakah, and the rest of the religious laws obligatory upon them. This was difficult for some of them, so Allah revealed this verse. He then consoled them, saying: “And We certainly tested those before them.”
“And We certainly tested those before them. So Allah will surely make evident those who are truthful, and He will surely make evident those who are liars. (3) Or do those who commit evil deeds think that they can outrun Us? Evil is their judgment! (4)”
“And We certainly tested those before them” means the prophets and the believers. Some of them were sawed apart with saws, while others were killed. The Children of Israel were tested through Pharaoh, who subjected them to the worst torment. 66/b “So Allah will surely make evident those who are truthful”—that is, truthful in their statement, “We believe”—“and He will surely make evident those who are liars.” Yet Allah knew them before the test. The meaning of the verse is that Allah will surely make the truthful distinct from the liars, until what He knew would occur comes to pass. Muqatil said: Allah will surely see. It was also said: Allah will surely distinguish them, as in His saying: “so that Allah may distinguish the wicked from the good” (al-Anfal 38).
“Or do those who commit evil deeds”—meaning polytheism—“think that they can outrun Us,” that is, evade and escape Us, so that We are unable to take vengeance upon them? “Evil is their judgment”: How evil was the judgment they made when they imagined this.