9. bow . . . made . . . naked--that is, was drawn forth from its cover, in which bows usually were cased when not in use. Compare Isa 22:6, "Kir uncovered the shield."
      according to the oaths of the tribes even thy word--that is, Thy oaths of promise to the tribes of Israel (Ps 77:8; Lu 1:73, 74). Habakkuk shows that God's miraculous interpositions for His people were not limited to one time, but that God's oaths to His people are sure ground for their always expecting them. The mention of the tribes, rather than Abraham or Moses, is in order that they may not doubt that to them belongs this grace of which Abraham was the depository [CALVIN and JEROME]. MAURER translates, "The spears were glutted with blood, the triumphal song!" that is, no sooner did Jehovah begin the battle by baring His bow, than the spears were glutted with blood and the triumphal song sung.
      Thou didst cleave the earth with rivers--the result of the earthquake caused by God's approach [MAURER]. GROTIUS refers it to the bringing forth water from the rock (Ex 17:6; Nu 20:10, 11; Ps 78:15, 16; 105:4). But the context implies not the giving of water to His people to drink, but the fearful physical phenomena attending Jehovah's attack on Israel's foes.

JFB.