It is difficult to determine the most prayerful man in history as prayer is a deeply personal and private practice. However, there have been many individuals throughout history who are known for their devout and dedicated prayer life. Some examples include:

1. Prophet Muhammad: The founder of Islam, Prophet Muhammad is known for his strong devotion to prayer. He prayed regularly and encouraged his followers to do the same.
2. Saint Francis of Assisi: A Catholic friar and preacher, Saint Francis of Assisi is known for his deep prayer life and connection to God. He spent hours in prayer and meditation, seeking spiritual guidance.
3. Mother Teresa: A Catholic nun and missionary, Mother Teresa dedicated her life to serving the poor and marginalized. Prayer was a central part of her daily routine, and she often said that she felt closest to God when in prayer.
4. Mahatma Gandhi: A spiritual and political leader in India, Mahatma Gandhi practiced prayer and meditation daily. He believed in the power of prayer to bring about social change and justice.
5. Saint Teresa of Ávila: A Spanish mystic and Carmelite nun, Saint Teresa of Ávila is known for her writings on prayer and mysticism. She emphasized the importance of prayer as a means of deepening one’s relationship with God.

These individuals are just a few examples of those who have been known for their deep prayer life and devotion to spiritual practices. Each person’s prayer life is unique and personal, and the most prayerful individual in history may be someone whose dedication and faith are known only to themselves and to God.