The Prophet of Allah ﷺ used to train horses by reducing their feed and then race them.
حدثنا مسدد حدثنا معتمر عن عبيد الله عن نافع
أن نبي الله ﷺ كان يضمر الخيل يسابق بها
Muslim narrated it, hadith no. 1870, from the hadith of Ubaydullah bin Umar, through the same chain. See the previous hadith: 2575.