Source: Infernal Machine Rebuild

Wondrous item, rare

This fine leather bridle tugs at the hand when first held, as though it longs to reach out for a beast nearby. When you hold one end of the bridle, you can use an action to speak its command word, causing the other end to lash out at a beast you can see within 20 feet of you. The target must succeed on a DC 17 Charisma saving throw or have the bridle tie itself around its neck, then fall under your command as if subjected to the Dominate Beast spell. Once the targeted is affected, you do not need to hold the other end of the bridle to command it. With a successful saving throw, the target becomes immune to the bridle’s power until the next dawn.

A creature controlled by the bridle can be released by the creature that bound it as a bonus action. A creature controlled by the bridle can make a DC 17 Charisma check each day at dawn. On a success, the creature is no longer affected by the bridle.