Genesis 49:17

New American Bible - revised edition

Let Dan be a serpent by the roadside, a horned viper by the path, That bites the horse’s heel, so that the rider tumbles backward.

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“Dan shall achieve justice for his people as one of the tribes of Israel.

“I long for your deliverance, O Lord!

From Naphtali: one thousand captains, and with them, armed with shield and lance, thirty-seven thousand men.

but in the end it bites like a serpent, and stings like an adder.

If the snake bites before it is charmed, then there is no advantage in a charmer.