Numbers 10

 “Make two silver trumpets for yourself; you shall make them of hammered work; you shall use them for calling the congregation and for directing the movement of the camps." v.2

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A trumpet is a common instrument in most every band or orchestra.  Its sound is powerful and beautiful.  Two silver trumpets were made for gathering and directing the people.  The trumpets were to be sounded only by the sons of Aaron, the priests.  At the sound of one trumpet the leaders of the tribes are to gather before Moses.  At the sound of both trumpets the whole community is to gather before Moses at the tent of meeting.  Then at certain trumpet blasts the tribes are to set out in a certain order.  The order seems to have the ark of the covenant in the middle as first it's the tribes to the east then to the south.  I can't help but think of The Sound of Music when the Captain has a different whistle blow for each of his twelve children and other whistle signals for specific commands.  It's ridiculous for kids but so beneficial for the population of Israel as the tribes were spread so far.
We then see how the sounding of the trumpets were for safety as they were to use the trumpet if being attacked by an enemy and then the Lord would rescue them.  Oh how I wish I had a trumpet to blow and be rescued every time I felt attacked by the enemy, Satan.  But we have something better than a trumpet for the Lord to remember us and rescue us: Jesus.  It may not seem immediate or saved from it, but He actually already did before we even sounded anything.  Yes we do wait the day for Jesus to return and bind Satan and rid all enemies, but because of the Holy Spirit we have prayer to sound out to Him now.  Do you trust God is listening to your battle cries?  What is the sound of your trumpet right now calling?