Not to disregard “the standards laid down by God” through His latest Manifestation

O Pen of the Most High! Say: O people of the world! We have enjoined upon you fasting during a brief period, and at its close have designated for you Naw-Ruz as a feast. Thus hath the Day-Star of Utterance shone forth above the horizon of the Book as decreed by Him Who is the Lord of the beginning and the end. … 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.

These are the ordinances of God that have been set down in the Books and Tablets by His Most Exalted Pen. Hold ye fast unto His statutes and commandments, and be not of those who, following their idle fancies and vain imaginings, have clung to the standards fixed by their own selves, and cast behind their backs the standards laid down by God. Abstain from food and drink from sunrise to sundown, and beware lest desire deprive you of this grace that is appointed in the Book. 

- Baha'u'llah  ('The Kitab-i-Aqdas')