From Xuanzang's Tang-dynasty 《
大唐西域记》 (Records of the Western Regions), describing the highest of nine grades of Buddhist salutation: touching the ground with the 'five parts' (
两手 two hands,
两膝 two knees,
头 head) — i.e. full prostration. Today used figuratively for total admiration, almost always with
佩服 (pèifú) —
佩服得五体投地 is the standard collocation.