Charles H. Spurgeon on Psalms 119:71

It is good for me that I have been afflicted. Even though the affliction came from bad men, it was overruled for good ends: though it was bad as it came from them, it was good for David. It benefited him in many ways, and he knew it. Whatever he may have thought while under the trial, he perceived himself to be the better for it when it was over. It was not good to the proud to be prosperous, for their hearts grew sensual and insensible; but affliction was good for the Psalmist. Our worst is better for us than the sinner's best. It is bad for sinners to rejoice, and good for saints to sorrow. A thousand benefits have come to us through our pains and griefs, and among the rest is this that we have thus been schooled in the law.

That I might learn thy statutes. These we have come to know and to keep by feeling the smart of the rod. We prayed the Lord to teach us (Psalms 119:66), and now we see how he has already been doing it. Truly he has dealt well with us, for he has dealt wisely with us. We have been kept from the ignorance of the greasy hearted by our trials, and this, if there were nothing else, is just cause for constant gratitude. To be larded by prosperity, is not good for the proud; but for the truth to be learned by adversity is good for the humble. Very little is to be learned without affliction. If we would be scholars we must be sufferers. As the Latins say, "Experientia docet", experience teaches. There is no royal road to learning the royal statutes; God's commands are best read by eyes wet with tears.