David was in great trials and afflictions, for God allows his children to fall into long and great afflictions and troubles before his deliverance comes. It is implied in the text that David was reproving his soul for being cast down. David realized that there was no good reason why he should be cast down, but there he was. It is a sin for a child of God to be too much discouraged and cast down in afflictions. The soul is cast down too much when our sorrow does not bring us to God, but away from God. There is no discouragement in any affliction or trouble whatsoever, but it is a lack of trusting in God. We may not know the reason God has allowed it, and this requires our trust. When we do not trust in God we are trusting in ourselves, and we cannot experience victory in our own strength. We need to trust in God for a constant supply. The reason why God’s children fail so, in times of trouble, is because they do not trust God for new supplies of grace. We cannot perform new duties, and undergo new sufferings, with old graces. Our soul is weak in itself. It needs something to rely upon as a weak plant that needs a support. David was in temptation, afflictions, and discouragements. Satan was tempting, and his corruptions boiling. God had withdrawn his sense of love, leaving David for a while to himself. At length, however, he broke through it all and expostulates the matter with himself. So God’s children, when they are in trouble, can recover and comfort themselves by trusting and relying on God in their extremities. The true child, in his greatest troubles, has the Spirit of God to strengthen him. He rests upon his God. In the greatest troubles, the Spirit helps our weakness. This Spirit enables us to send out strong prayers and cries, which cry loud in God’s ear.
RICHARD SIBBES, Works, VII: 51-55