Benson Commentary
Habakkuk 3:17-18. Although the fig-tree shall not blossom — Though all outward means of support should fail, yet will I still have a FIRM CONFIDENCE in the Power, Goodness, and Faithfulness of God, that He will preserve me, and supply me with all things necessary; and therefore, amidst the most threatening appearances of affairs, I shall still preserve inward peace and serenity of mind, as trusting in Him in whom is everlasting strength, Isaiah 26:3-4. “You will keep in perfect and constant peace the one whose mind is steadfast [that is, committed and focused on You—in both inclination (a person's natural tendency or urge to act or feel in a particular way) and character],
Because he trusts and takes refuge in You [with hope and confident expectation]. 4 “Trust [confidently] in the Lord forever [He is your fortress, your shield, your banner], For the Lord God is an everlasting Rock [the Rock of Ages].”

The state of the land during the captivity may be here prophetically described, when the vineyards, olive-yards, fields, and pastures, would be in a desolate and barren state: or the prophet may be considered as declaring, that even such circumstances should not shake his confidence in God. Yet will I rejoice in the Lord — I shall have him to rejoice in, and will rejoice in him. I will joy in the God of my salvation —

In the knowledge and love, the favour and friendship, the care and kindness of Him in whom I have present, and hope to have future and eternal salvation. Observe reader; this is the principal ground of our joy in God, that He is the God of our salvation; our everlasting salvation, the salvation of our souls; and if He be so, we may rejoice in Him as such in our greatest distresses, since by them our salvation cannot be hindered, but may be furthered.