The 246th mitzvah is that we are commanded regarding claims and counterclaims [in lawsuits].

The source of this commandment is G‑d's statement1 (exalted be He), "In every case of dishonesty... [and the watchman] said that this is it."

In the words of the Mechilta: "The phrase 'that this is it' refers to partial admission to the claim."2

This mitzvah includes anything that can arise from the claims people have against one another involving admission and denial.

The details of this commandment are explained in the 3rd chapter of Bava Kama, the beginning of Bava Metzia, and the 5th, 6th, and 7th chapters of Shavuos. Many questions regarding this subject are spread throughout the Talmud.