And they took their bones and buried them in the wood of Jabes: and fasted seven days.

and they take their bones, and bury them under the tamarisk in Jabesh, and fast seven days.

And their bones they put in the earth under a tree in Jabesh; and for seven days they took no food.

And they took their bones, and they buried them in the forest of Jabesh. And they fasted for seven days.

Under a tree - Rather, "Under the tamarisk," a well-known tree at Jabesh which was standing when this narrative was written.
They fasted seven days - In imitation of the mourning for Jacob (marginal reference). They would give full honor to Saul though he was fallen.

And fasted seven days - To testify their sincere regret for his unfortunate death, and the public calamity that had fallen upon the land.
Thus ends the troublesome, and I had almost said the useless, reign of Saul. A king was chosen in opposition to the will of the Most High; and the government of God in effect rejected, to make way for this king.
Saul was at first a very humble young man, and conducted himself with great propriety; but his elevation made him proud, and he soon became tyrannical in his private conduct and in his political measures. His natural temper was not good; he was peevish, fretful, and often outrageous; and these bad dispositions, unchecked by proper application to the grace of God, became every day more headstrong and dangerous. Through their violence he seems at times to have been wholly carried away and deranged; and this derangement appears to have been occasionally greatly exacerbated by diabolical influences. This led him to take his friends for his foes; so that in his paroxysms he strove to imbrue his hands in their blood, and more than once attempted to assassinate his own son; and most causelessly and inhumanly ordered the innocent priests of the Lord at Nob to be murdered. This was the worst act in his whole life.
Saul was but ill qualified for a proper discharge of the regal functions. The reader will remember that he was chosen rather as a general of the armies than as civil governor. The administration of the affairs of the state was left chiefly to Samuel, and Saul led forth the armies to battle.
As a general he gave proof of considerable capacity; he was courageous, prompt, decisive, and persevering; and, except in the last unfortunate battle in which he lost his life, generally led his troops to victory.
Saul was a weak man, and very capricious; this is amply proved by his unreasonable jealousy against David, and his continual suspicion that all were leagued against him. It is also evident, in his foolish adjuration relative to the matter of the honey (see 1-Samuel 14:24-30, 1-Samuel 14:38-44) in which, to save his rash and nonsensical oath, he would have sacrificed Jonathan his son!
The question, "Was Saul a good king?" has already in effect been answered. He was on the whole a good man, as far as we know, in private life; but he was a bad king; for he endeavored to reign independently of the Jewish constitution; he in effect assumed the sacerdotal office and functions, and thus even changed what was essential to that constitution. He not only offered sacrifices which belonged to the priests alone; but in the most positive manner went opposite to the orders of that God whose vicegerent he was.
Of his conduct in visiting the woman at En-dor I have already given my opinion, and to this I must refer. His desperate circumstances imposed on the weakness of his mind; and he did in that instance an act which, in his jurisprudential capacity, he had disapproved by the edict which banished all witches, etc., from Israel. Yet in this act he only wished to avail himself of the counsel and advice of his friend Samuel.
To the question, "Was not Saul a self-murderer?" I scruple not to answer, "No." He was to all appearance mortally wounded, when he begged his armor-bearer to extinguish the remaining spark of life; and he was afraid that the Philistines might abuse his body, if they found him alive; and we can scarcely say how much of indignity is implied in this word; and his falling on his sword was a fit of desperation, which doubtless was the issue of a mind greatly agitated, and full of distraction. A few minutes longer, and his life would in all probability have ebbed out; but though this wound accelerated his death, yet it could not be properly the cause of it, as he was mortally wounded before, and did it on the conviction that he could not survive.
Taking Saul's state and circumstances together, I believe there is not a coroner's inquest in this nation that would not have brought in a verdict of derangement; while the pious and the humane would everywhere have consoled themselves with the hope that God had extended mercy to his soul.
Millbrook, June 11, 1818.
Ended this examination August 13, 1827. - A.C.

And they took their bones, and buried [them] under a tree at Jabesh, and (f) fasted seven days.
(f) According to the custom of mourners.

And they took their bones, and buried them under a tree at Jabesh,.... For though they burned the bodies, yet so as to preserve the bones; and these, together with the ashes of the parts burnt, they gathered up, and buried under a tree near this city; this tree is said to be an oak, 1-Chronicles 10:12; so Deborah, the nurse of Rebekah, was buried under an oak, Genesis 35:8. The Jews generally interred their dead under some oak, as aforementioned writer observes (q); pleased perchance with the parallel, as he expresses it, that as these plants, seemingly dead in winter, have every spring an annual resurrection, so men's dry bones shall have new sap put into them at the day of judgment:
and fasted seven days; not that they ate and drank nothing all that time, but they fasted every day till evening, as the Jews used to do; so long it seems a man may live without eating, but not longer; See Gill on Exodus 24:18 and see Gill on 1-Kings 19:8; this they did, as Kimchi thinks, in memory of the seven days Nahash the Ammonite gave them for their relief, in which time Saul came and saved them, 1-Samuel 11:3.
(q) Pisgah-Sight of Palestine b. 2. ch. 2. p. 82.

Fasted - To testify their sorrow for the loss of Saul, and of the people of God; and to intreat God's favour to prevent the utter extinction of his people. But you must not understand this word of fasting strictly, as if they eat nothing for seven whole days; but in a more large sense, as it is used both in sacred and profane writers; that they did eat but little, and that but mean food, and drank only water for that time. This book began with the birth of Samuel, and ends with the death of Saul: The comparing these together will teach us to prefer the honour that comes from God, before all the honours of the world.