For thou shalt heap
chathah (khaw-thaw')
to lay hold of; especially to pick up fire -- heap, take (away).
coals of fire
gechel (geh'-khel)
from an unused root meaning to glow or kindle; an ember -- (burning) coal.
upon his head
ro'sh (roshe)
the head (as most easily shaken), whether literal or figurative (in many applications, of place, time, rank, itc.)
and the LORD
Yhovah (yeh-ho-vaw')
(the) self-Existent or Eternal; Jehovah, Jewish national name of God -- Jehovah, the Lord.
shall reward
shalam (shaw-lam')
to be safe (in mind, body or estate); figuratively, to be (causatively, make) completed; by implication, to be friendly; by extension, to reciprocate
thee