Nine holy days require the suspension of work: Naw-Rúz; the first, ninth and twelfth days of Ridván; the Declaration of the Báb on 23 May; the Ascension of Bahá'u'lláh on 29 May; the Martyrdom of the Báb on 9 July; and the twin birthdays of the Báb and Bahá'u'lláh, kept on consecutive days in the autumn. Two further anniversaries — the Day of the Covenant and the Ascension of 'Abdu'l-Bahá — are commemorated but do not require abstention from work. Several of the holy days begin at a specified hour: the Declaration of the Báb at two hours and eleven minutes after sunset, the Ascension of Bahá'u'lláh at three in the morning, the Martyrdom of the Báb at noon, and Bahá'ís gather at those times. The practical difficulty everywhere outside the small number of countries with Bahá'í populations is employment: the obligation resolves in practice into asking for leave nine times a year, and Bahá'í institutions advise members on how to do so.