Achan's Execution (Joshua 7:24, 25)

Joshua 7

King James Version (KJV)

24 And Joshua, and all Israel with him, took Achan the son of Zerah, and the silver, and the garment, and the wedge of gold, and his sons, and his daughters, and his oxen, and his asses, and his sheep, and his tent, and all that he had: and they brought them unto the valley of Achor.

25 And Joshua said, Why hast thou troubled us? the Lord shall trouble thee this day. And all Israel stoned him with stones, and burned them with fire, after they had stoned them with stones.

Comments:

Previously, in verse 15, God said:

And it shall be, that he that is taken with the accursed thing shall be burnt with fire, he and all that he hath: because he hath transgressed the covenant of the Lord, and because he hath wrought folly in Israel.

However, it appears that this was not a command to burn Achan alive, but to burn him after he was put to death (which was by stoning). 

In his Bible commentary, Matthew Poole writes:

Quest. How could both these deaths be inflicted upon them ? Answ. It seems they were stoned to death, which was the punishment of such offenders, Lev. xxiv. 14 ; Numb. xv. 35, and not burned to death; and therefore the stoning only of Achan is mentioned here, and not his burning; and God would have their dead carcasses burned to show his utmost detestation of such persons as break forth into sins of such a public scandal and mischief. And for the burning of Achan, commanded ver. 15, it seems not likely to be meant of his burning alive, because that burning is common to him, and all that he hath, as is there expressed ; but of the burning of his dead carcass, and other lifeless things, as the manner was with accursed things, Deut. xiii. 16.

And Matthew Henry writes: 

He was stoned (some think as a sabbath breaker, supposing that the sacrilege was committed on the sabbath day), and then his dead body was burnt, as an accursed thing, of which there should be no remainder left. The concurrence of all the people in this execution teaches us how much it is the interest of a nation that all in it should contribute what they can, in their places, to the suppression of vice and profaneness, and the reformation of manners; sin is a reproach to any people, and therefore every Israelite indeed will have a stone to throw at it.