See here, 1. That it has been the lot of the best saints to be afflicted. The proud and the wicked lived in pomp and pleasure, while David, though he kept close to God and his duty, was still in affliction. Waters of a full cup are wrung out to God’s people, Psalms 73:10. 2. That it has been the advantage of God’s people to be afflicted. David could speak experimentally: It was good for me; many a good lesson he had learnt by his afflictions, and many a good duty he had been brought to which otherwise would have been unlearnt and undone. Therefore God visited him with affliction, that he might learn God’s statutes; and the intention was answered: the afflictions had contributed to the improvement of his knowledge and grace. He that chastened him taught him. The rod and reproof give wisdom. MHBCC 598.62