John Gill Commentary 1 Samuel 31:12

"all the valiant men arose, and went all night, and took the body of Saul and the bodies of his sons from the wall of Beth-shan; and they came to Jabesh, and burnt them there." — 1 Samuel 31:12 (ASV)

All the valiant men arose
Of the city of Jabeshgilead, fired with indignation at the Philistines' ill usage of Saul and the bodies of his sons:

and went all night ;
not only for secrecy, but for haste:

and took the body of Saul and the bodies of his sons from the wall of
Bethshan, and came to Jabesh ;
brought them with them thither, the Philistines either having no knowledge of it, or not daring to oppose them:

and burnt them there :
that is, the flesh of them, for the bones they buried, as in (1 Samuel 31:13) ; and this they did, contrary to the common usage of the country, which was not to burn; but this they did, that if the Philistines should come to recover them, they would not be able to do it: though the Targum is, ``they burnt over them, as they burn over their kings there;'' they made a burning for them of spices over them; or of their beds, and other household goods, as Kimchi and Ben Melech observe, though they prefer the other sense; see (2 Chronicles 16:14) (21:19) perhaps the true reason might be, because they were putrid and infectious.