Vital Vow of Visz

You and another target each make a vow to the other which must be fulfilled before the spell ends, or the targets that fail will suffer the consequences. When both vows are made the thread ties itself to one of each of the target's pinkies then disappears. For the duration of the spell you each can feel the faint tug from the thread on your pinky, and are aware of its binding strength.

Both targets must first hear eachother's vow then agree to both of them. Nether target can be under duress by the other target or their allies. Both targets must be made aware of the consequence of the spell. If any of these conditions are not met the spell cannot be cast.

If a target has not fulfilled their vow to the letter within the spell’s duration, they fall under the Betrayer's Curse and receive a point of exhaustion. While under the Betrayer's Curse, points of exhaustion given by this spell cannot be removed. This curse can be removed by the Remove Curse spell or a Wish spell.

At Higher Levels. When you cast this spell using a spell slot of 3rd level or higher add an additional point of exhaustion for each slot level over 2nd up 7th level.