The Bab, in the Persian Bayan, first instituted a nineteen day cycle of gatherings as part of the calendar he laid out for his community, built on nineteen months of nineteen days each. Baha'u'llah confirmed the observance for his own followers in the Kitab-i-Aqdas, his book of laws, establishing it as a recurring obligation of Baha'i community life rather than an occasional or optional gathering, though the text itself gives little detail about how a feast should be conducted.
That detail was supplied later, chiefly by Shoghi Effendi, the appointed head of the Baha'i community from 1921 to 1957, who set out the feast's now standard threefold division into a devotional portion of prayer and scripture reading, an administrative portion for community consultation, and a social portion of shared food and conversation. The threefold structure was designed to hold together the community's spiritual life, its practical governance at the local level, and its social bonds within a single recurring occasion, rather than separating them into different kinds of meetings held at different times. Local communities that have not yet elected a Local Spiritual Assembly, or that are too small to sustain one, still hold the feast where possible, since its devotional and social functions do not depend on the presence of an elected administrative body in the way the consultative portion does.