Romans 14:5

Esteemeth one day above another; because the ceremonial law, which he erroneously thinks is still binding, makes a distinction between different days of the week. One observes the Jewish feasts and fasts, the other does not. The apostle here has no reference to the difference of days spoken of in the moral law. He speaks in this chapter about that difference which is associated with meats and drinks, divers washings, and various other things contained in the ceremonial law.

Be fully persuaded; let a man examine and ascertain by the best light he can what is right, and do as he conscientiously believes that God requires. He should not, in such matters, be forced to follow another's conscience, but should be permitted, in the exercise of his inalienable right, to follow his own.