al-Zulm is interpreted in four ways.
1. The word al-Zulm is interpreted as shirk (associating partners with God); as in the following verses:
As for those who believe and do not mix their iman (faith) with zulm {that is, shirk}... (al-Anʿām 6:82)
(Luqman said to his son): "O my son! Do not associate anything with Allah. Indeed, shirk (associating partners with God) is a great zulm." (Luqmān 31:13)
2. The term zulm is used in the sense of a servant wronging himself by committing an error—other than shirk;
as in the following verses:
Do not retain them to harm them and transgress against their rights. Whoever does that has certainly wronged himself (i.e., has committed zulm against himself due to his error). (al-Baqara 2:231)
(Moses said): "My Lord! Indeed, I have wronged myself (by killing a man), so forgive me!" So He forgave him. (al-Qaṣaṣ 28:16)
When such statements are made regarding the people of tawhid (the oneness of God), what is meant is wronging the nafs (the lower self) due to an error committed.
3. The term al-Ẓālimīn is used for those who wrong other people; as in the following verses:
The retribution for an evil act is an evil one like it, but whoever pardons and makes reconciliation, his reward is with Allah. Indeed, He does not like the ẓālimīn (i.e., those who initiate wrongdoing against others). (al-Shūrā 42:40)
...The blame is only upon those who wrong people and transgress upon the earth without right. (al-Shūrā 42:42)
4. The term yuzlamūn is used in the sense of those who are harmed without doubt and whose (rewards or rights) are diminished; as in the following verse:
Eat from the good things with which We have provided you (that is, from manna and quails). (al-Baqara 2:57)
Allah had commanded them to take from these [manna and quails] only as much as they needed for each day, and not to take more. But they disobeyed Him in this matter. Thus, the statement of the Exalted Allah, They did not wrong Us (i.e., by taking and storing more than their daily need of manna and quails, they did not harm Us nor diminish anything from Us).
But they wronged themselves (al-Baqara 2:57) expresses this.
We shall set up the scales of justice for the Day of Resurrection, so no soul will be wronged at all (i.e., nothing will be diminished from anyone). (al-Anbiyāʾ 21:47)
They will not be wronged even as much as the weight of a speck (i.e., not the least of their deeds will be diminished). (Maryam 19:60)