Psalms 55:16-17
16 But I call to God, and the LORD will save me.
17 Evening and morning and at noon I utter my complaint and moan, and he hears my voice.

Daniel 6:10 When Daniel knew that the document had been signed, 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.

Acts 10:9 The next day, as they were on their journey and approaching the city, Peter went up on the housetop about the sixth hour to pray.

Matthew Henry says:

David perseveres in his resolution to call upon God, being well assured that he should not seek him in vain (Psalm 55:16)… He resolves to be both fervent and frequent [see below] in this duty…

He will pray frequently, every day, and three times a day - evening, and morning, and at noon. It is probable that this had been his constant practice, and he resolves to continue it now that he is in his distress. Then we may come the more boldly to the throne of grace in trouble when we do not then first begin to seek acquaintance with God, but it is what we have constantly practised, and the trouble finds the wheels of prayer going. Those that think three meals a day little enough for the body ought much more to think three solemn prayers a day little enough for the soul, and to count it a pleasure, not a task. As it is fit that in the morning we should begin the day with God, and in the evening close it with him, so it is fit that in the midst of the day we should retire awhile to converse with him. It was Daniel’s practice to pray three times a day (Daniel 6:10), and noon was one of Peter’s hours of prayer, Acts 10:9. Let not us be weary of praying often, for God is not weary of hearing. “He shall hear my voice, and not blame me for coming too often, but the oftener the better, the more welcome.”

If you would like some models of morning and evening prayers you can find some here:
http://www.eternallifeministries.org/prayers.htm