Charles H. Spurgeon on Psalms 119:67

Before I was afflicted I went astray. Partly, perhaps, through the absence of trial. Often our trials act as a thorn hedge to keep us in the good pasture, but our prosperity is a gap through which we go astray. If any of us remember a time in which we had no trouble, we also probably recollect that then grace was low and temptation was strong. It may be that some believer cries, "O that it were with me as in those summer days before I was afflicted." Such a sigh is most unwise, and arises from a carnal love of ease: the spiritual man who prizes growth in grace will bless God that those dangerous days are over, and that if the weather be more stormy it is also more healthy. It is well when the mind is open and candid, as in this instance: perhaps David would never have known and confessed his own straying if he had not smarted under the rod. Let us join in his humble acknowledgments, for doubtless we have imitated him in his straying. Why is it that a little ease works in us so much disease? Can we never rest without rusting? Never be filled without waxing fat? Never rise as to one world without going down as to another! What weak creatures we are to be unable to bear a little pleasure! What base hearts are those which turn the abundance of God's goodness into an occasion for sin.

But now have I kept thy word. Grace is in that heart which profits by its chastening. It is of no use to plough barren soil. When there is no spiritual life affliction works no spiritual benefit; but where the heart is sound trouble awakens conscience, wandering is confessed, the soul becomes again obedient to the command, and continues to be so. Whipping will not turn a rebel into a child; but to the true child a touch of the rod is a sure corrective. In the Psalmist's case the medicine of affliction worked a change "but"; an immediate change "now"; a lasting change "have I" an inward change "have I kept"; a change towards God "thy word." Before his trouble he wandered, but after it he kept within the hedge of the word, and found good pasture for his soul the trial tethered him to his proper place; it kept him, and then he kept God's word. Sweet are the uses of adversity, and this is one of them, it puts a bridle upon transgression and furnishes a spur for holiness.