Charles Ellicott Commentary 1 Samuel 20:34

"So Jonathan arose from the table in fierce anger, and did eat no food the second day of the month; for he was grieved for David, because his father had done him shame." — 1 Samuel 20:34 (ASV)

So Jonathan arose. —In fierce anger, so runs the all too true record. The son of Saul left the king's presence and appeared no more at that fatal feast.

His hot anger was stirred up, first, no doubt, by the terrible insult offered him, the prince and heir to the throne, before the assembled prominent men of Israel. The great spear uplifted to strike, following the harsh and bitter words spoken, was an act not likely to be soon forgotten by the spectators. And secondly, by the determined and relentless enmity of Saul against David, of whose stainless integrity and perfect loyalty Jonathan was firmly convinced. The bitter wrong done to David his friend no doubt affected Jonathan the most.