Rashi: They are to pay a man like his actions.

R. Yonah #1: There are five verses here about the Midos of kings. Shlomo interrupted with this verse, for Hashem's Mishpat will never cease. Sometimes a mortal king does not want proper judgment, and he vindicates the Rasha. And sometimes the Emes is hidden from him, even though his mouth does not trespass ¹ , and the Rasha is saved from the king's judgment.

R. Yonah #2: All these verses are about the Midos of kings. They are to make one put to heart that Hashem gives to kings' hearts to recognize injustice and investigate the Emes. He helps them, so no matter will evade their investigation in Mishpat. All the more so His Mishpat is Tzedek! This is why this verse is among these verses about kings. Also Chazal proved about the ways of Hashem's Midos from verses about kings' Midos. E.g. one who has a Choleh in his house should go to a Chacham to request mercy for him - "Chamas Melech Mal'achei Maves v'Ish Chacham Yechaperenah" (14; Bava Basra 116a). It also brings about Tzedakah given covertly "Matan ba'Seser Yichpeh Af" (21:14). Any verse in this Sefer that its simple meaning does not discuss Yir'as Hashem, is like a Mashal, so people will learn to fear Hashem from it.

Malbim: Peles is greater than Mozenayim. Here it discusses measuring the Magal - the roundabout path, to measure from the current location to the destination. On a Mozenayim one puts what is weighed in one pan, and the weights on the other pan, to see if they are equal. Hashem has Peles to weigh a person's ways, conduct and Magalosav, to direct them towards straightness. Also refer to 16:11:2:3.

Rashi: Just like there are big and small stone weights - everything is according to man's actions.

R. Yonah: It means Ma'asehu b'Kol Avnei Kis. The prefix Beis is omitted. Kis is the Kli in which they store weights, lest they be ruined - "Lo Yihyeh b'Chisecha" (Devarim 25:13). Hashem does not refrain from punishing for light matters - deeds, thoughts or spoken words. All weights of Mishpat are his. The Mashal is, it is as if He weighs, with a scale, great, intermediate and small weights. So He judges great and small matters - "Hineni Shole'ach l'Dayagim Rabim" (Yirmeyah 16:16).

Malbim: Hashem also has Mozenei Mishpat to weigh one's deeds, and bestow to him good or evil according to his Midos. What stone weights does Hashem put on the scale? They are Ma'asehu. He arranged every deed that He did, to weigh people's deeds of choice. He puts man's deeds on one pan, and Hashem's deeds, ways of nature and the Ma'arachah, correspondingly opposite to them. "v'Hayah Im Shamo'a Tishme'u El Mitzvosai v'Nasati Metar Artzechem b'Ito;