John Gill

But turned back,.... From God and his worship, apostatized from the true religion, and turned to idols: and dealt unfaithfully, like their fathers; in the wilderness; see Psa 78:8, they were turned aside like a deceitful bow; that promises well to carry the arrow right, but drops it at the feet of the archer; or carries it another way, so that it misses the mark, The Targum is, "as a bow casting arrows;'' to the ground, and not to the mark; see Hos 7:16, or being too much stretched is suddenly broken, and kills the archer; or returns to its own nature; so Arama.