Psalm 55:16–17 (ESV)

16 But I call to God, and the LORD will save me.

After the plea to curse his enemies, the author comes with his confession: But I call upon God, and the Lord will save me. The beginning of the Psalm is already a prayer (Psalm 55:1–2). There it sounds like a plea—perhaps unsure, almost desperate. Now it is a sure confession: the Lord will save me upon my prayer. And praying is the author’s lifeline. He prays in the evening, in the morning, and in the afternoon.

Here we recognize the three times of prayer and the bringing of sacrifices of the Old Testament covenant people. For example, Daniel was familiar with Darius’ law to petition no one but the king, yet we read in Daniel 6:10 that he went to his house where he had windows in his upper chamber open toward Jerusalem. He got down on his knees three times a day and prayed and gave thanks before his God, as he had done previously.

Two other passages on the power of prayer are 1 Thessalonians 5:17 (pray without ceasing), and Luke 18:1 (they ought always to pray and not lose heart).