ספֿרי מצוות אויף ויקרא 5:1

And the sin-offering over what is concealed.

And that is that He commanded us to testify in court about everything that we know. Whether the testimony about one will bring a death penalty or save him, or [save] his money or destroy it - we are obligated to testify about all of this and to inform the judges about that which we have seen or heard. And behold that they brought a proof about the obligation of telling over testimony from His, may He be blessed, saying, "and is a witness, whether he has seen or known of it" (Leviticus 5:1). And the punishment for one who transgresses this commandment and suppresses his testimony is great. And that it His saying, "if he do not utter it, then he shall bear his iniquity." And this is a general matter. But if the testimony he suppressed was testimony about money, and he denied it and swore falsely [about it], he is liable for a variable offering, as is explained by Scripture, according to the stipulations mentioned in Shevuot. And the regulations of this commandment have already been explained in Sanhedrin. (See Parashat Vayikra; Mishneh Torah, Testimony 9.)