Adam Clarke on Habakkuk 3:19

The Lord God is my strength - This is an imitation, if not a quotation, from Psa 18:32-33 (note), where see the notes.

Will make me to walk upon mine high places - This last verse is spoken in the person of the people, who seem to anticipate their restoration; and that they shall once more rejoice in the hills and mountains of Judea.

To the chief singer on my stringed instruments - This line, which is evidently a superscription, leads me to suppose that when the prophet had completed his short ode, he folded it up, with the above direction to the master singer, or leader of the choir, to be sung in the temple service. Many of the Psalms are directed in the same way. "To the master singer;" or, "chief musician;" to be sung, according to their nature, on different kinds of instruments, or with particular airs or tunes.

Neginoth, נגינות which we translate stringed instruments, means such as were struck with a plectrum, or excited by some kind of friction or pulsation; as violins and cymbals or tambourines are. I do not think that the line makes any part of the prophecy, but merely the superscription or direction of the work when it was finished. The ending will appear much more dignified, this line being separated from it.