Fasting and prayer have been marks of repentance for Jews and Christians for millennia. Wednesdays and Fridays were fast days for Christians since the earliest centuries of Christian history. Four times a year, the Ember days (the Wednesday, Friday, and Saturday after December 13; the day after the first Sunday of Lent; the day after Pentecost Sunday; and the day after September 14) were special days for repentance and fasting. The most rigorous monastic orders followed a more restricted diet...
Solemn national assemblies for prayer, fasting, and repentance are described in the Old Testament Scriptures. In America, local and national leaders have called for days of prayer and fasting at times of crisis and when they perceive a need for repentance by the entire society. In 1989 Southern Baptist leaders issued a call to prayer and solemn assembly.
The solemn assembly movement is based on 2 Chronicles 7:14. In this passage the people of Israel were challenged to fast and pray and in doing so repent of their wicked ways. This national approach is applied in the solemn assembly movement to an individual congregation based on New Testament Christian practices.
This example of planning and holding of a weekend solemn assembly comes from Southern Baptists in Texas. The movement in Texas grew out of several retreats for leaders of Texas Baptist men's groups at which the Holy Spirit caused a spirit of revival to break out, leading to brokenness, repentance, confession, and prayer.