וְעִבְרִ֗ים עָֽבְרוּ֙ אֶת־הַיַּרְדֵּ֔ן אֶ֥רֶץ גָּ֖ד וְגִלְעָ֑ד וְשָׁאוּל֙ עוֹדֶ֣נּוּ בַגִּלְגָּ֔ל וְכָל־הָעָ֖ם חָרְד֥וּ אַחֲרָֽיו׃
Now some of the Hebrews had gone over the Jordan to the land of Gad and Gilead; but as for Saul, he was yet in Gilgal, and all the people followed him trembling.
Chizkuni
ויחרד כל העם, in this instance the root חרד does not mean that the people were afraid, but the meaning is similar to Samuel I 14,15: המצב והמשחית חרדו, “the garrison and the spoilers also made a commotion.” See also Samuel I 13,7: וכל העם חרדו אחריו, “and all the people rallied to him.” When they heard the voices, even though they were still in their beds, they rallied to their appointed positions near the mountain.