Up, sanctify the people, and say, Sanctify yourselves against tomorrow: for thus says Yahweh, the God of Israel, There is a devoted thing in the midst of you, Israel; you can not stand before your enemies, until you take away the devoted thing from among you.
The burning of a criminal after his stoning was one way of emphasizing the wickedness of his crime (Leviticus 20:14; cf. Deuteronomy 13:15-16). It was a "disgraceful thing" (Joshua 7:15) to steal something under the ban (devoted to God).