Or HaChaim on Genesis 44:9/אור החיים על בראשית מ״ד:ט׳

1 אשר ימצא אתו מעבדיך ומת, "whichever of your servants it will be found with shall die, etc." Gentiles are subject to the death penalty for theft (Sanhedrin 54); the brothers offered themselves as slaves in addition