All in Writings and Guidance
The First day of Riḍván refers to Bahá’u’lláh’s arrival in a garden outside the city of Baghdád, subsequently referred to as the Garden of Riḍván. This event…in April 1863, signalized the commencement of the period during which Bahá’u’lláh declared His Mission to His companions.
Naw-Rúz is the first day of the new year. It coincides with the spring equinox in the Northern Hemisphere, which usually occurs on 21 March. Bahá’u’lláh explains that this feast day is to be celebrated on whatever day the sun passes into the constellation of Aries (i.e. the vernal equinox), even should this occur one minute before sunset. Hence Naw-Rúz could fall on 20, 21, or 22 March, depending on the time of the equinox (Notes from The Kitáb-i-Aqdas).
Bahá’u’lláh enjoined upon His followers to devote these days (26 February to 1 March 2019, inclusive) to feasting, rejoicing and charity. In a letter written on Shoghi Effendi’s behalf it is explained that “the intercalary days are specially set aside for hospitality, the giving of gifts, etc.”
O ye beloved friends of God and handmaids of the Merciful! Call ye to mind the blessed Name of our peerless Beloved, the Abhá Beauty, in an uplifting spirit of unbounded ecstasy and delight…
Having sent forth Mullá ‘Alí on his mission, the Báb summoned to His presence the remaining Letters of the Living, and to each severally He gave a special command and appointed a special task and addressed to them these parting words.