Genesis 49:17

And let Dan be a serpent in the way, besetting the path, biting the heel of the horse (and the rider shall fall backward),

Dan shall be a serpent by the way, an adder in the path, that biteth the horse heels, so that his rider shall fall backward.

Dan will be a serpent on the trail, an adder in the path, that bites the horse’s heels, so that his rider falls backward.