Leviticus 27:32-33 ▼

32 For every tithe of the herd or flock, whatever passes under the [shepherd’s] staff, the tenth one shall be holy to the LORD.

33 The man is not to be concerned whether the animal is good or bad, nor shall he exchange it. But if he does exchange it, then both it and its substitute shall become holy; it shall not be redeemed.’”