Charles H. Spurgeon on Psalms 56:3

What time I am afraid, etc. A divine spark may live in a smoke of doubts without a speedy rising into flame. When grace is at the bottom of doubting, there will be reliance on Christ and lively petitions to him. Peter's faith staggers when he began to sink, but he casts a look and sends forth a cry to his Saviour, acknowledging his sufficiency; Mt 14:30, "Lord, save me." Sometimes those doubtings strengthen our trust and make us take hold faster on God. Ps 56:3. What time I am afraid, I will trust in thee. This was a fear of himself or others, rather than a jealousy of God. Had he had unworthy suspicions of him, he would not have trusted him; he would not have run for remedy to the object of his fear. The waverings where faith is, are like the tossings of a ship fast at anchor (still there is a relying upon God), not like a boat carried by the waves of the sea to be dashed against a rock. If the heart stay on Christ in the midst of those doubtings, it is not an evil heart of unbelief. Such doubtings consist with the indwelling of the Spirit, who is in the heart, to perform the office of a Comforter against such fears and to expel those thick fumes of nature. Stephen Charnock.