He expected to feel a sword severing his head. David's gift was more than a hand out. True friendship will be generous. David parted with a large valuable estate. Love is like that.
Love is unselfish.
Love is extravagant. When you love God's church you are generous with it. When you love God you give Him all you have. I don't read that David said anything about the young man's disfigured legs. It was never mentioned.