When ye blow an alarm, then the camps that lie on the {b} east parts shall go forward.

(b) That is, the host of Judah and they that are under his ensign.

Matthew Henry's Concise Commentary

10:1-10 Here are directions concerning the public notices to be given the people by sound of trumpet. Their laws in every case were to be Divine, therefore, even in this matter Moses is directed. These trumpets typify the preached gospel. It sounds an alarm to sinners, calls them to repent, proclaims liberty to the captives and slaves of Satan, and collects the worshippers of God. It directs and encourages their heavenly journey; stirs them up to combat against the world and sin, encouraging them with the assurance of victory. It leads their attention to the sacrifice of Christ, and shows the Lord's presence for their protection. It is also necessary that the gospel trumpet give a distinct sound, according to the persons addressed, or the end proposed; whether to convince, humble, console, exhort, reprove, or teach. The sounding of the trumpet of the gospel is God's ordinance, and demands the attention of all to whom it is sent.