Albert Barnes Commentary Hosea 5:8

"Blow ye the cornet in Gibeah, and the trumpet in Ramah: sound an alarm at Beth-aven; behind thee, O Benjamin." — Hosea 5:8 (ASV)

Blow you the cornet in Gibeah - The evil day and destruction, denounced, is now vividly pictured as actually present. All is in confusion, hurry, and alarm, because the enemy was in their midst.

The “cornet,” an instrument made of horn, was to be blown as the alarm when the enemy was near. The “trumpet,” in contrast, was especially used for the worship of God.

“Gibeah and Ramah” were cities of Benjamin on the borders of Ephraim, where the enemy, who had taken control of Israel, would burst into Judah. From Bethaven or Bethel, the seat of Ephraim’s idolatry on the border of Benjamin, the outcry of destruction was to break forth: after you, O Benjamin; the enemy is upon you, just behind you, pursuing you.

God had promised His people, if they would serve Him, I will make all your enemies turn their backs to you (Exodus 23:27), and had threatened the contrary if they should walk contrary to Him.

Now that threat was to be fulfilled fully. The ten tribes are spoken of as already under the enemy's control, and he was “upon Benjamin,” who was fleeing before them.