To testify their sorrow for the public loss of Saul, and of the people of God; and to entreat 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 and general sense, as it is used both in sacred and profane writers; that they did eat but little, and that seldom, and that but mean food, and drunk only water for that time.
Related Commentaries of 1 Samuel 31:13
1 Samuel 31:13
13 And they took their bones, and buried them under a tree at Jabesh, and fasted seven days.