al-Mustazʿafūn is interpreted in three ways.
1. al-Mustazʿafūn [the mustazʿafs] means 'those who have been subjugated/oppressed [those who have been rendered weak]'; as in the following verses:
We were mustazʿafs {that is, those who have been subjugated, rendered weak} in the land {that is, in Mecca}. (al-Nisāʾ/97)
What is [the matter] with you that you do not fight in the cause of Allah and [for] the mustazʿaf {that is, the subjugated, rendered weak} men, women, and children? (al-Nisāʾ/75)
Indeed, Pharaoh exalted himself in the land [in Egypt] and made its people into factions, oppressing a group among them {that is, the Children of Israel} as mustazʿaf {that is, (he subjugated / rendered weak) enslaved them}. (al-Qaṣaṣ/4)
But We wanted to favor those who were mustazʿaf {that is, those rendered weak in the land of Mecca} in the land... (al-Qaṣaṣ/5)
2. The word al-Mustazʿafīn [the mustazʿafs] means the weak ones who follow the leaders in kufr (disbelief); as in the following verses:
The mustazʿafs {that is, those who follow the leaders (in disbelief)} will say to the arrogant ones ({that is, the leaders whom they followed in disbelief}), "If it had not been for you, we would have been believers." The arrogant ones {that is, the (disbelieving) leaders whom the mustazʿafs followed} will say to the mustazʿafs {that is, those who followed them}, "Did we avert you from guidance after it had come to you? Rather, you were criminals." The mustazʿafs {that is, those who follow the leaders of disbelief} will say to the arrogant ones (that is, the leaders whom they followed)... (Sabaʾ/31-33)
3. The expression al-Mustazʿafīn [the mustazʿafs] is used in the sense of those who are powerless and helpless; as in the following verses:
Except for the mustazʿafs (that is, powerless and helpless) among men, women, and children... (al-Nisāʾ/98)
There is not upon the weak {that is, the powerless and helpless}, nor upon the ill, nor upon those who do not find anything to spend [in charity], any blame (for staying behind from battle). (al-Tawba/91)