Charles H. Spurgeon on Psalms 119:4

Diligently. For three causes should we keep the commandments of the Lord with diligence: first, because our adversary that seeks to snare us by the transgression of them is diligent in tempting, for he goes about, night and day, seeking to devour us; next, because we ourselves are weak and infirm, by the greater diligence have we need to take heed to ourselves; thirdly, because of the great loss we sustain by every vantage Satan gets over us; for we find by experience, that as a wound is sooner made than it is healed, so guiltiness of conscience is easily contracted, but not so easily done away. William Cowper.