Negative commandment · Lo Ta’aseh #304 of 613
Not to take revenge
שלא לנקום
The verse · Vayikra 19:18
לֹא־תִקֹּם וְלֹא־תִטֹּר אֶת־בְּנֵי עַמֶּךָ וְאָהַבְתָּ לְרֵעֲךָ כָּמוֹךָ אֲנִי ה׳
“Thou shalt not avenge, nor bear any grudge against the children of thy people, but thou shalt love thy neighbour as thyself: I am the Lord.”
The Rambam’s words
Not to take revenge, as [Leviticus 19:18] states: "Do not take revenge."
שלא לנקום, שנאמר "לא תיקום" (ויקרא יט,יח).
Why · Sefer HaChinuch #241
To not avenge
“It is from the roots of the commandment that a person know and put into his heart that everything that happens to him — good and bad — the cause of it coming to him is from G-d, blessed be He.”
Who & when
“And [it is] practiced in every place and at all times by males and females.”
Where in the Mishneh Torah
Hilchot Human Dispositions הלכות דעות