Should a reining horse stop from the rider's seat or reins?

Ideally, a finished reining horse should stop primarily from the rider's seat and body — with the reins supporting and shaping the stop rather than forcing it. The seat cue comes first: the rider sits deep, drives the hips slightly forward, stills the following motion of the lope, and says whoa, and the horse responds to that combination by engaging its hindquarters and beginning the stop before the rein is ever applied. The rein then arrives as a refinement and a guide — maintaining softness through the poll and jaw, keeping the horse's head and neck in the correct position through the slide, and reinforcing the stop if the horse does not fully commit from the seat alone. A reining horse that requires a hard pull to stop on every run has not been trained to read the seat — it has been trained to respond to rein pressure alone, which means the rein must always be the primary cue and the stop will only be as good as the amount of rein the rider can apply. This creates a ceiling on the quality of the stop and on the horse's longevity, because a horse stopped by force thousands of times accumulates both physical stress and mental resistance that a horse stopped by a willing seat cue does not. Building a seat-cued stop requires patience and a deliberate training progression: install the response at slow speeds before expecting it at fast ones, reward the horse for any try toward the seat cue before the rein is needed, and consistently release the rein the moment the horse responds so that the seat cue becomes more meaningful than the rein over time. The goal is a horse that reads the rider's body and offers the stop, with the rein present as a guide rather than as the engine driving the maneuver.