Ye shall set the city on fire, to wit, part of it, as a sign to their brethren of their success; for the whole city was not burnt now, but afterwards, as is said Joshua 8:28.
Related Commentaries of Joshua 8:8
Joshua 8:8
8 And it shall be, when ye have taken the city, that ye shall set the city on fire: according to the commandment of the LORD shall ye do. See, I have commanded you.