The two trumpets were to be made of one piece of silver, reminding us of the Old and New Testaments both of which are really one — the Word of God. Redemption is pictured to us in the silver.
V.2 For the calling of the assembly.
V.4-10 An alarm for time of war, and even in the days of gladness and in their solemn days. The Word of God is for every purpose — it can and should be part of that joy, as well as for protection and comfort.
V.11-12 The perfect order of the camp as it begins to move onward.
V.29 Moses made a mistake here, and turns to a relative, who was familiar with the wilderness, and asks him to guide them and to be to them instead of eyes (v. 31). Sometimes we are guided by relatives instead of the Word and the Holy Spirit.
V.33-34 The Lord is jealous, for He knows that guidance from elsewhere will lead us into wrong paths. So He instructs that they take the ark out of the center of the camp and put it at the front to guide. Notice what He was seeking for them. Are you finding rest for your soul?