Rashi and Targum Onkelos: It withholding the wages or delaying payment of a poor laborer.

Targum Yonasan: It prohibits withholding the wages of a regular laborer or delaying payment (or changing the agreed upon wages of a poor laborer. ¹

Rashi: Because whereas "Re'acha" incorporates everybody, rich and poor alike, the current Pasuk comes to add an additional La'av if the laborer is a poor man.

Bava Metzi'a, 111a: Because someone who withholds the wages of a laborer transgresses five ¹ La'avin ² 1 & 2 "Lo Sa'ashok es Re'acha ve'Lo Sigzol" (Kedoshim Vayikra, 19:13); 3. "Lo Sa'ashok Sachir Oni" (the current Pasuk); 4. "Lo Salin" (Kedoshim Vayikra, 19:13); 5. "ve'Lo Savo alav ha'Shemesh" (the current Pasuk); and one Asei "be'Yomo Titen Secharo." (Pasuk 15). ³

Rashi: "Ani" is 'a poor man', ¹ "Evyon", someone who is destitute ² (and the Torah gives precedence to an Ani - Bava Metzi'a, 111a).

Rashi: Refer to 24:14:2:1.

Ramban #1: Because it is common ¹ to withhold the wages of an Ani and an Evyon. ²

Ramban #2 (citing the Sifri): The Torah mentions "Ani" and "Evyon" to teach us that Hashem hastens to punish quicker on their behalf more than on behalf of others.

Bava Metzi'a 111b: The Torah mentions "Ani ve'Evyon" to teach us that one pays a poor laborer before a rich one, and an Oni before an Evyon (since the latter will not allow shame to stop him from asking for his wages - Rashi). ³

Ramban (citing the Sifri): To teach us that someone who holds back the wages of a convert transgresses two La'avin. ¹

Rashi: To incorporate a Ger Toshav - a Nochri who [undertakes to keep the seven Mitzvos Bnei No'ach, but who] eats Neveilos.

Rashi: To include in the Isur withholding the rental owed for animals and vessels. ¹