Sukkah 30A

משום דהוה ליה מצוה הבאה בעבירה, שנאמר: ״והבאתם גזול ואת הפסח ואת החולה״. גזול דומיא דפסח, מה פסח לית ליה תקנתא ⁠— אף גזול לית ליה תקנתא, לא שנא לפני יאוש ולא שנא לאחר יאוש.

It is unfit because it is a mitzva that comes to be fulfilled by means of a transgression, which renders the mitzva unfulfilled, as it is stated: “And you have brought that which was stolen and the lame, and the sick; that is how you bring the offering; should I accept this of your hand? says YHWH” (Malachi 1:13). Based on the juxtaposition in the verse, it is derived that the legal status of a stolen animal is equivalent to that of a lame animal. Just as a lame animal, because it is blemished, has no remedy and is unfit for use, so too, a stolen animal has no remedy. There is no difference before the owners reach a state of despair of recovering the stolen animal, and there is no difference after despair. In both cases there is no remedy.

בשלמא לפני יאוש ⁠— ״אדם כי יקריב מכם״ אמר רחמנא, ולאו דידיה הוא. אלא לאחר יאוש ⁠— הא קנייה ביאוש! אלא לאו, משום דהוה ליה מצוה הבאה בעבירה.

The Talmud elaborates: Granted, before the despair of the owner, the robber may not sacrifice the animal because the animal does not belong to him. God says: “When a person sacrifices from yours an offering” (Leviticus 1:2). The term “from yours” indicates that the animal must belong to the one sacrificing it, and this stolen animal is not his. However, after the despair of the owner, didn’t the robber acquire the animal with the despair? Once the owner despairs, the animal belongs to the robber, despite the fact that he incurs a debt that he must repay the owner. Since the animal is legally his, why is it prohibited for the robber to sacrifice it as an offering? Rather, is it not because the offering is a mitzva that comes by means of a transgression? Since the animal came into his possession by means of a transgression, it is unfit for use in fulfilling a mitzva.