Charles H. Spurgeon on Psalms 51:15

O Lord, open thou my lips. He is so afraid of himself that he commits his whole being to the divine care, and fears to speak till the Lord unstops his shame silenced mouth. How marvellously the Lord can open our lips, and what divine things can we poor simpletons pour forth under his inspiration! This prayer of a penitent is a golden petition for a preacher, Lord, I offer it for myself and my brethren. But it may stand in good stead any one whose shame for sin makes him stammer in his prayers, and when it is fully answered, the tongue of the dumb begins to sing. And my mouth shall shew forth thy praise. If God opens the mouth he is sure to have the fruit of it. According to the porter at the gate is the nature of that which comes out of a man's lips; when vanity, anger, falsehood, or lust unbar the door, the foulest villainies troop out; but if the Holy Spirit opens the wicket, then grace, mercy, peace, and all the graces come forth in tuneful dances, like the daughters of Israel when they met David returning with the Philistine's head.