Tafsir of Al Imran 3:128-129

{أو يتوب عليهم} This is a conjunction linked to what precedes it.

{ليس لك من الأمر شيء} This is a parenthetical clause. The meaning is: God is the Master of their affair; He may either destroy them, defeat them, or turn to them in forgiveness if they submit, or punish them if they persist in disbelief. You have no authority over their affair; you are merely a servant sent to warn them and strive against them.

It is said that {يتوب} is in the accusative case due to an implied an (that). Thus, an yatūba (that He may forgive) is effectively a noun conjoined by aw (or) to al-amr (the affair) or to shay’ (anything). The meaning is: "You have no share in their affair, nor in forgiving them, nor in punishing them," or "You have no share in their affair, or in the forgiving of them, or in the punishing of them."

It is also said that aw (or) carries the meaning of illā an (unless/except that), similar to your saying: "I will surely stay with you, or you give me my right," meaning: You have no share in their affair, except that God may turn to them in forgiveness—so you rejoice at their state—or He may punish them—so you find relief from them.

It is said that Utbah ibn Abi Waqqas wounded him [the Prophet] on the day of Uhud and broke his incisor. He began wiping the blood from his face, while Salim, the freedman of Abu Hudhayfah, washed the blood from his face, saying: "How can a people prosper who have stained the face of their Prophet with blood while he calls them to their Lord?" Then this was revealed.

It is also said that he [the Prophet] intended to invoke God against them, so God the Exalted forbade him, for He knew that among them were those who would believe.

Regarding {يغفر لمن يشاء} (He forgives whom He wills): It is from Al-Hasan that He does not will to forgive except those who repent. Regarding {ويعذب من يشاء} (And He punishes whom He wills): He does not will to punish except those who deserve punishment. From ‘Ata’: He forgives whoever repents to Him, and He punishes whoever meets Him while being a wrongdoer and his followers.

His saying: {أو يتوب عليهم أو يعذبهم فإنهم ظالمون} This is an explanation clarifying who is forgiven—those who repent—and who are the wrongdoers. However, the people of whims and innovations turn a deaf ear and a blind eye to the verses of God, stumbling blindly. They satisfy themselves with what they fabricate against Ibn Abbas, claiming that He grants forgiveness for a major sin to whom He wills, and punishes whom He wills for a minor sin.