2 Samuel 1:12
And they mourned, and wept, and fasted until even, for Saul, and for Jonathan his son, and for the people of the LORD, and for the house of Israel; because they were fallen by the sword. And they mourned, and wept, and fasted until even, for Saul, and for Jonathan his son, and for the people of the LORD, and for the house of Israel; because they were fallen by the sword.
David and his men mourned Saul, Jonathan, the people of the Lord, and the house of Israel because they had fallen by the sword in battle. Their mourning included weeping and fasting until evening. They grieved for Saul in this way even though he had persecuted David.