In Yehoshua 7:15 God tells Yehoshua that when he finds the man that took from the forbidden booty of Jericho he should punish him with burning. Yet at the end of that very chapter in verse 25 Achan is punished by stoning, not burning. Why is that?
Rashi comments on verse 15 that God’s instruction that he “he shall be burnt with fire” refers to Achan’s tent and movable property. In verse 25 he explains that “all Yisrael stoned him with stones” because he had violated the Shabbos (the looting of Jericho took place on the Shabbos). Rashi seems to understand that God’s instruction to burn did not refer Achan.
But the Ralbag writes that both punishments were meted out to Achan - stoning for violating the Shabbos, and burning for violating the ban on looting. He also brings another explanation in the name of his father, that they burned Achan as per God’s instruction, but they also threw stones at him on the way to be burnt because they were very angry at him.