From Ole Hallesby‘s classic work Prayer, published in 1931:

Here the purpose and meaning of prayer dawned upon me for the first time. Here I was privileged to see more clearly than ever before the purpose of prayer: to glorify the name of God.

The scales fell from my eyes. I saw in a new light the misuse of prayer and the difficulties connected with prayer as well as the place of our own efforts in prayer.

Prayer life has its own laws, as all the rest of life has. The fundamental law in prayer is this: Prayer is given and ordained for the purpose of glorifying God. Prayer is the appointed way of giving Jesus an opportunity to exercise His supernatural powers of salvation. And in so doing He desires to make use of us.

We should through prayer give Jesus the opportunity of gaining access to our souls, our bodies, our homes, our neighborhoods, our countries, to the whole world, to the fellowship of believers and to the unsaved.

If we will make use of prayer, not to wrest from God advantages for ourselves or our dear ones, or to escape from tribulations and difficulties, but to call down upon ourselves and others those things which will glorify the name of God, then we shall see the strongest and boldest promises of the Bible about prayer fulfilled also in our weak, little prayer life. Then we shall see such answers to prayer as we had never thought were possible.

(Pages 127-128)