The First Day of Ridván commemorates Bahá'u'lláh's arrival at the Garden of Ridván in Baghdad in 1863 and His public declaration of His prophetic mission. Thirty-one days after Naw-Rúz, Bahá'u'lláh left His house, crossed the Tigris River, and entered the garden, where He announced to His companions that He was the Promised One foretold in all religions . This day is observed as one of the three major holy days of the twelve-day Ridván festival, on which Bahá'ís suspend work and school if possible . Bahá'u'lláh referred to it as the "Day of supreme felicity," and it is regarded as the most significant event of His ministry and the founding moment of the Bahá'í Faith .