Why We Celebrate
Let the days in excess of the months be placed before the month of fasting. We have ordained that these, amid all nights and days, shall be the manifestations of the letter Há, and thus they have not been bounded by the limits of the year and its months. It behoveth the people of Bahá, throughout these days, to provide good cheer for themselves, their kindred and, beyond them, the poor and needy, and with joy and exultation to hail and glorify their Lord, to sing His praise and magnify His Name; and when they end --these days of giving that precede the season of restraint--let them enter upon the Fast. Thus hath it been ordained by Him Who is the Lord of all mankind. The traveller, the ailing, those who are with child or giving suck, are not bound by the Fast; they have been exempted by God as a token of His grace. He, verily, is the Almighty, the Most Generous.
Bahá'u'lláh, The Kitab-i-Aqdas, p. 25