Answer: The whole Word of God is of use to direct us in the duty of prayer₁; but the special rule of direction is that form of prayer which our Savior Christ taught his disciples, commonly called the Lord’s Prayer₂.

1. 1 John 5:14
2. Matt 6:9-13; Luke 11:2-4

For further study see:

1. WLC 183: For whom are we to pray?
2. WLC 184: For what things are we to pray?
3. WLC 185: How are we to pray?