The Birth of Bahá'u'lláh is a Bahá'í holy day commemorating the birth of Mírzá Husayn-'Alí, the founder of the Bahá'í Faith, who was born in 1817 in Tehran, Persia . Observed annually as the second of the "Twin Holy Birthdays" (following the Birth of the Báb), its date follows a lunar calculation and in 2026 falls on November 11 . Bahá'ís mark the occasion with community gatherings, readings from sacred texts, prayers, music, and shared meals, and it is one of the nine holy days on which work is suspended .