A Commentary, Critical, Practical, and Explanatory on the Old and New Testaments, by Robert Jamieson, A.R. Fausset and David Brown  at sacred-texts.com
1 Kings (1 Samuel) 31:1
sa1 31:1SAUL HAVING LOST HIS ARMY AT GILBOA, AND HIS SONS BEING SLAIN, HE AND HIS ARMOR-BEARER KILL THEMSELVES. (Sa1 31:1-7)
Now the Philistines fought against Israel--In a regular engagement, in which the two armies met (Sa1 28:1-4), the Israelites were forced to give way, being annoyed by the arrows of the enemy, which, destroying them at a distance before they came to close combat, threw them into panic and disorder. Taking advantage of the heights of Mount Gilboa, [the Israelites] attempted to rally, but in vain. Saul and his sons fought like heroes; but the onset of the Philistines being at length mainly directed against the quarter where they were, Jonathan and two brothers, Abinadab or Ishui (Sa1 14:49) and Melchishua, overpowered by numbers, were killed on the spot.
1 Kings (1 Samuel) 31:3
sa1 31:3the battle went sore against Saul, &c.--He seems to have bravely maintained his ground for some time longer; but exhausted with fatigue and loss of blood, and dreading that if he fell alive into the enemy's hands, they would insolently maltreat him (Jos 8:29; Jos 10:24; Jdg 8:21), he requested his armor bearer to despatch him. However, that officer refused to do so. Saul then falling on the point of his sword killed himself; and the armor bearer, who, according to Jewish writers, was Doeg, following the example of his master, put an end to his life also. They died by one and the same sword--the very weapon with which they had massacred the Lord's servants at Nob.
1 Kings (1 Samuel) 31:6
sa1 31:6So Saul died--(see on Ch1 10:13; Hos 13:11).
and his three sons--The influence of a directing Providence is evidently to be traced in permitting the death of Saul's three eldest and most energetic sons, particularly that of Jonathan, for whom, had he survived his father, a strong party would undoubtedly have risen and thus obstructed the path of David to the throne.
and all his men, that same day together--his servants or bodyguard (Ch1 10:6).
1 Kings (1 Samuel) 31:7
sa1 31:7the men of Israel that were on the other side of the valley--probably the valley of Jezreel--the largest and southernmost of the valleys that run between Little Hermon and the ridges of the Gilboa range direct into the Jordan valley. It was very natural for the people in the towns and villages there to take fright and flee, for had they waited the arrival of the victors, they must, according to the war usages of the time, have been deprived either of their liberty or their lives.
1 Kings (1 Samuel) 31:8
sa1 31:8THE PHILISTINES TRIUMPH OVER THEIR DEAD BODIES. (Sa1 31:8-10)
on the morrow, when the Philistines came to strip the slain, that they found Saul and his three sons fallen--On discovering the corpses of the slaughtered princes on the battlefield, the enemy reserved them for special indignities. They consecrated the armor of the king and his sons to the temple of Ashtaroth fastened their bodies on the temple of Shen, while they fixed the royal heads ignominiously in the temple of Dagon (Ch1 10:10); thus dividing the glory among their several deities.
1 Kings (1 Samuel) 31:10
sa1 31:10to the wall-- (Sa2 21:12) --"the street" of Beth-shan. The street was called from the temple which stood in it. And they had to go along it to the wall of the city (see Jos 17:11).
1 Kings (1 Samuel) 31:11
sa1 31:11THE MEN OF JABESH-GILEAD RECOVER THE BODIES AND BURY THEM AT JABESH. (Sa1 31:11-13)
the inhabitants of Jabesh-gilead heard of that which the Philistines had done--Mindful of the important and timely services Saul had rendered them, they gratefully and heroically resolved not to suffer such indignities to be inflicted on the remains of the royal family.
1 Kings (1 Samuel) 31:12
sa1 31:12valiant men arose, and went all night, and took the body of Saul and the bodies of his sons--Considering that Beth-shan is an hour and a half's distance, and by a narrow upland passage, to the west of the Jordan (the whole being a journey from Jabesh-gilead of about ten miles), they must have made all haste to travel thither to carry off the headless bodies and return to their own side of the Jordan in the course of a single night.
burnt them--This was not a Hebrew custom. It was probably resorted to on this occasion to prevent all risk of the Beth-shanites coming to disinter the royal remains for further insult.