Positive commandment · Mitzvat Aseh #236 of 613
For a person who injures [a colleague] to pay him damages
להיות החובל משלם ממון
The verse · Shemot 21:18
וְכִי־יְרִיבֻן אֲנָשִׁים וְהִכָּה־אִישׁ אֶת־רֵעֵהוּ בְּאֶבֶן אוֹ בְאֶגְרֹף וְלֹא יָמוּת וְנָפַל לְמִשְׁכָּב
“And if men strive together, and one smite another with a stone, or with his fist, and he die not, but keeps his bed:”
The Rambam’s words
For a person who injures [a colleague] to pay him damages, as [Exodus 21:18] states: "If men will quarrel and one man will strike [his colleague]...."
להיות החובל משלם ממון, שנאמר: "וכי יריבון אנשים--והכה איש" (שמות כא,יח).
Why · Sefer HaChinuch #49
Laws of penalties
“The root of this commandment — and more generally, everything that the Torah commanded about the matter of law — does not require me to exert myself to [find] its reason for the matter.”
Who & when
“And this commandment that we are obligated to judge and to punish one who injures is practiced by males, as it was given to them to administer justice; not by women (Talmud Yerushalmi Sanhedrin 3:9), who do not judge.”
Where in the Mishneh Torah
Hilchot One Who Injures a Person or Property הלכות חובל ומזיק