Isaiah 40:29
"He giveth power to the faint; and to them that have no might he increaseth strength."
Cross References (ranked by relevance)
Fear thou not; for I am with thee: be not dismayed; for I am thy God: I will strengthen thee; yea, I will help thee; yea, I will uphold thee with the right hand of my righteousness.
I can do all things through Christ which strengtheneth me.
Strengthened with all might, according to his glorious power, unto all patience and longsuffering with joyfulness;
And I will strengthen them in the LORD; and they shall walk up and down in his name, saith the LORD.
For I have satiated the weary soul, and I have replenished every sorrowful soul.
The LORD will give strength unto his people; the LORD will bless his people with peace.
The Lord GOD hath given me the tongue of the learned, that I should know how to speak a word in season to him that is weary: he wakeneth morning by morning, he wakeneth mine ear to hear as the learned.
Thy shoes shall be iron and brass; and as thy days, so shall thy strength be.
Quenched the violence of fire, escaped the edge of the sword, out of weakness were made strong, waxed valiant in fight, turned to flight the armies of the aliens.
But his bow abode in strength, and the arms of his hands were made strong by the hands of the mighty God of Jacob; (from thence is the shepherd, the stone of Israel:)