Charles H. Spurgeon on Psalms 39:12

Hear my prayer, O Lord, etc. Now, in this prayer of David, we find three things, which are the chief qualifications of all acceptable prayers. The first is humility. He humbly confesses his sins, and his own weakness and worthlessness. We are not to put on a stoical, flinty kind of spirit under our affliction, that so we may seem to shun womanish repinings and complaints, lest we run into the other evil, of despising the hand of God, but we are to humble our proud hearts, and break our unruly passions...The second qualification of this prayer is, fervency and importunity, which appears in the elegant gradation of the words, Hear my prayer, my words; if not that, yet, Give ear to my cry, which is louder; and if that prevail not, yet, Hold not thy peace at my tears, which is the loudest of all; so David, elsewhere, calls it the voice of weeping. ...The third qualification is faith. "He who comes to God must believe that he is, and is a rewarder of them that diligently seek him." Heb 11:6. And, certainly, as he that comes to God must believe this, so he that believes this, cannot but come to God; and if he be not presently answered, "he that believes makes no haste, "he resolves patiently to wait for the Lord, and go to no other. Condensed from Robert Leighton.