הלכה על ויקרא 5:3

That is that He commanded us to return the stolen item itself, if it is still remaining as itself - with the addition of a fifth if he swore [about it] - or to give its value, if it was transformed. And that is His, may He be exalted, saying, "and he shall return the stolen item" (Leviticus 5:3). And they already explained in Tractate Makkot (Makkot 16a) that the negative commandment of robbery is a negative commandment that is rectified by a positive commandment. And they said [about this] that Scripture said, "you shall not rob" (Leviticus 19:13), "and he shall return the stolen item." And the regulations of this commandment have already been explained in Bava Kamma. (See Parashat Vayikra; Mishneh Torah, Robbery and Lost Property 1.)