postrar

to prostrate, lie prostrate, to lie low; to prostrate oneself, to kneel, to fall to one's knees (in obedience, to beg etc.); to debilitate

Dissimilated from Old Spanish prostrar (e.g. prostrado in Gonzalo de Berceo, 13th century), a borrowing from Medieval Latin prōstrāre, backformed from prōstrātus, perfect passive participle of prōsternō (“to prostrate, to throw down”).