“Call upon me in the day of trouble;
I will deliver you, and you shall glorify me.” —Psalm 50:15

And call upon me in the day of trouble. Oh blessed verse! Is this then true sacrifice? Is it an offering to ask an alms of heaven? It is even so. The King himself so regards it. For herein is faith manifested, herein is love proved, for in the hour of peril we fly to those we love. It seems a small thing to pray to God when we are distressed, yet is it a more acceptable worship than the mere heartless presentation of bulls and goats. This is a voice from the throne, and how full of mercy it is! It is very tempestuous round about Jehovah, and yet what soft drops of mercy’s rain drop from the bosom of the storm! Who would not offer such sacrifices? Troubled one, haste to present it now! Who shall say that Old Testament saints did not know the gospel? Its very spirit and essence breathes like frankincense all around this holy Psalm. 

I will deliver thee. The reality of thy sacrifice of prayer shall be seen in its answer. Whether the smoke of burning bulls be sweet to me or no, certainly thy humble prayer shall be, and I will prove it so by my gracious reply to thy supplication. This promise is very large, and may refer both to temporal and eternal deliverances; faith can turn it every way...

And thou shalt glorify me. Thy prayer will honor me, and thy grateful perception of my answering mercy will also glorify me. The goats and bulls would prove a failure, but the true sacrifice never could. The calves of the stall might be a vain oblation, but not the calves of sincere lips. Thus we see what is true ritual. Here we read inspired rubrics. Spiritual worship is the great, the essential matter; all else without it is rather provoking than pleasing to God.

—Charles Spurgeon, Treasury of the Psalms