Al-Hadid: 28
"O you who have believed"
Abu Hayyan has established that the address is intended for those who believed from the Ummah of the Prophet (may Allah exalt him and grant him peace), excluding the People of the Scripture, and the traditions support this. Al-Tabarani recorded in al-Awsat on the authority of Ibn Abbas, and Ibn Abi Hatim on the authority of Sa'id ibn Jubayr, that they both said: Forty of the Negus’s companions came to the Prophet (may Allah exalt him and grant him peace) and witnessed the battle of Uhud with him. They sustained injuries, but none of them were killed. When they saw the need the believers were in, they said: "O Messenger of Allah, we are people of means, so permit us to bring our wealth to assist the Muslims." Consequently, Allah the Almighty revealed regarding them: "Those to whom We gave the Scripture before it, they are believers in it" up to His saying: "Those will be given their reward twice for having been patient" (28:52-54). Thus, He granted them a double reward. When this verse was revealed, they said: "O community of Muslims, whoever among us has believed in your Scripture has two rewards, and whoever has not believed in your Scripture has [a reward] like your rewards." Thereupon, Allah the Almighty revealed: "O you who have believed"—the verse—meaning, in refutation of their statement: "And whoever has not believed in your Scripture has a reward like your rewards."
In al-Kashshaf, it is stated that those who said this were the ones who had not yet believed from among the People of the Scripture, and they said it when they heard that verse, boasting about it to the Muslims. The meaning is: O you who have been characterized by faith, fear Allah—remain steadfast in His piety, may He be exalted and glorified, regarding what He has forbidden you—and believe in His Messenger—remain steadfast in faith in His Messenger whom He has sent to you, who is Muhammad (may Allah exalt him and grant him peace). There is, in expressing it thus, an indication—which is not hidden—of the greatness of his status, peace and blessings be upon him.
"He will give you" —by virtue of that— "two portions of His mercy."
Abu Musa al-Ash'ari said: "It means 'two-fold' in the Abyssinian tongue." Others have said: "Two shares." The intent is to grant them two rewards, just like the believers among the People of the Scripture. It is as if it were said: He will grant you what was promised to those who believed from the People of the Scripture, namely the two rewards, because you are like them in believing in the preceding messengers and in the Seal of them all (may Allah exalt them all), not distinguishing between any of His messengers.
Al-Raghib said: "The kifl (portion) is the share that is sufficient, as if one has undertaken the responsibility for his affair." The two portions are those desired by His saying: "Our Lord, give us in this world [that which is] good and in the Hereafter [that which is] good," and there is no evidence for specific limitation.
"And He will make for you light by which you walk" —on the Day of Resurrection—and it is the light mentioned in His saying: "Their light will proceed before them and on their right"— "and He will forgive you" —what has passed of your sins— "and Allah is Forgiving, Merciful," meaning excessive in forgiveness and mercy; therefore, it is no wonder if He, the Almighty, does what He does.