a thousand: Twelve thousand in all - a small number in proportion to all Israel, or to the forces which they had to encounter. As they were under the conduct of captains of thousands and hundreds, they probably had no general; for Phinehas seems to have accompanied them simply to take charge of "the holy instruments;" probably the ark and silver trumpets.
Phinehas: Numbers 25:7-13
the holy instruments: Numbers 14:44, Numbers 33:20-22; Exodus 25:9; Joshua 6:4-6, Joshua 6:13-15; 1 Samuel 4:4-5, 1 Samuel 4:17, 1 Samuel 14:18; 1 Samuel 23:9; 2 Samuel 11:11
to blow: Numbers 10:8-9; 2 Chronicles 13:12-15