They instruct us to pronounce the words of short prayers and of all kinds of prayer without haste, observing scrupulous attention to the words of the prayers.
When the prayers are read unhurriedly, it is possible to have such attention, while hurried reading leaves no place for attention.
Prayer without attention is like a body which the soul has left: it has no fragrance of humility, it does not ascend to God.
Stricken and deadened by dispersed thoughts, it crawls along the earth of corruption and foul smell, imparting this corruption to those who pray carelessly and coldly.
Mental attention at prayer is reflected in the heart by blessed grief over sins, which is that very repentance that God commands us to have.
When the heart is filled with a feeling of repentance, it in turn draws the mind to increased attention.
Once there is attention and tender feeling, all the gifts of the Holy Spirit enter into the soul, making it a temple of God.
Let us provide our prayer with two qualities: attention and repentance. Let it fly up to the heavens with them as upon two wings, then appear before the face of God, and intercede for us to gain His mercy.
The blessed publican’s prayer had these two qualities. Penetrated by the awareness of his sinfulness, he did not have any hope in his own deeds to receive salvation; he had hope only in God’s mercy, which calls all sinners to repentance, and grants them salvation for repentance alone.
As a sinner who had no goodness of his own, the publican took the last place in the temple. As a sinner who is unworthy of heaven, he did not dare to lift his eyes unto heaven.
His eyes were directed toward the ground; and beating upon his heart with repentance from deep within his heart, he pronounced with his whole soul the prayer united with his confession: God be merciful to me, a sinner.
His prayer was so effective and strong, that the sinner left the temple of God justified.
Ignatius Brianchaninov (1807–1867; Russian Orthodox): Homily on the Sunday of the Publican and the Pharisee on Prayer and Repentance translated by Nun Cornelia Rees @ Pravoslavie.