Prayer is the key of the morning and the bolt of the night.

Often presented as a devotional maxim about beginning and ending the day with prayer; it circulates widely in religious quotation collections and sermons.

The saying frames prayer as something that opens the day with guidance and closes it with protection or peace, emphasizing a daily rhythm of spiritual dependence.

Prayer is the key of the morning and the bolt of the evening.

Prayer is the key to the morning and the bolt to the night.