This is a promise indeed!
Here is an urgent occasion — “the day of trouble.” It is dark at noon on such a day, and every hour seems blacker than the one which came before it. Then is this promise in season: it is written for the cloudy day.
Here is condescending advice, “Call upon me.” We ought not to need the exhortation: it should be our constant habit all the day and every day. What a mercy to have liberty to call upon God! What wisdom to make good use of it! How foolish to go running about to men! The LORD invites us to lay our case before Him, and surely we will not hesitate to do so.
Here is reassuring encouragement: “I will deliver thee.” Whatever the trouble may be, the LORD makes no exceptions but promises full, sure, happy deliverance. He will Himself work out our deliverance by His own hand. We believe it, and the LORD honors faith.
Here is an ultimate result: “Thou shalt glorify me.” Ah, that we will do most abundantly. When He has delivered us we will loudly praise Him; and as He is sure to do it, let us begin to glorify Him at once.(C.H. Spurgeon)