'Heavy' in the Bible

But Moses hands were heavy; and they took a stone, and put it under him, and he sat thereon; and Aaron and Hur stayed up his hands, the one on the one side, and the other on the other side; And his hands were steady until the going down of the sun.

Thou wilt surely wear away, both thou, and this people that is with thee: for the thing is too heavy for thee; thou art not able to perform it thyself alone.