Again, the common meaning of ghafara (forgiving) is not applicable here.

Again, the common meaning of ghafara (forgiving) is not applicable here. The word “ghafara” also means “to watch over someone” or “to guard someone” or “to cover something [i.e., protect it]”.

This second meaning does not imply any sin; it just means that by accidentally killing the oppressor, Músa found himself in harm and trouble from the people of Fir'awn; and, therefore, he prays ”…therefore, guard me and Allah guarded him.” This meaning of the last sentence is also supported by another verse of the Qur'an which quotes Allah saying to Músa that, “…when you killed an [Egyptian] man [accidentally and were being pursued by Fir'awn's people], We delivered you from the worry…” (20:40) So the dhulm is explained in this verse as “worry”; and “ghafara” is explained as “delivered”.