Rashi: [He oppresses the poor to increase for himself] wealth. R. Yonah - he sins for his own benefit.

Malbim #1: Even though he does not intend to oppress him, just he wants [to delay] the money [that he should give to the Oni] like a loan, and he will give Ribis to the Oni, so afterwards he can give to him much at once [this is called Oshek Dal]. Even if he does not keep the money in his hand, rather, he gives it to an Ashir, so it will be in his hand with Ribis ¹ , Ach l'Machsor" (it will only be a loss).

Malbim #2: If he withholds the wage of an Oni, so he will gather for him much wages at once, and remove him from the status of an Oni to the status of an Ashir, when he gives to him later, he becomes an Ashir. Even though he thinks that he benefits him greatly, it is only a loss. He oppressed the Dal and gave to an Ashir. At the time of the oppression, the Oni suffered the shame of hunger and pressure. What does it help that later, he gives to him when he is an Ashir? How will he bear the sin that he caused him to suffer pressure and lack? Navon is one who arranges all his actions to bring a good end, to reach them in a good and proper way. If not, will be like one who makes a true deduction via a false comparison.

Rashi: [One who oppresses the poor,] in the end he will give from his money to idolaters; he will come to lack.

R. Yonah: One who gives a gift to an Ashir, he sins. Chazal ¹ applied to this "Lema'an Sefos ha'Ravah Es ha'Tzeme'ah" (Devarim 29:18). This is sin without benefit; he only loses. The Ashir thinks that the giver was honored via his acceptance. Also, most who love money are stingy, therefore he will not return [the benefit]. Squandering money is a great sin. It shows that Tzedakah and Gemilus Chasadim are disgraced in his eyes. If he knew the power of Tzedakah, he would give his gift to an Oni, instead of squandering it!

Malbim: Refer to 22:16:1:2-3.