Quest. LXXXI. May we lawfully keep the Lord's day as a fast?

Answ. Not ordinarily; because God hath made it a day of thanksgiving; and we must not pervert it from the use to which it was appointed by God. But in case of extraordinary necessity, it may be done: as, 1. In case that some great judgment call us so suddenly to humiliation and fasting, as that it cannot be deferred to the next day (as some sudden invasion, fire, sickness, &c.) 2. In case by persecution the church be denied liberty to meet on any other day, in a time when public fasting and prayer is a duty. 3. In case the people be so poor, or servants, children, and wives be so hardly restrained, that they cannot meet at any other time. It is lawful in such cases, because positives give way to moral or natural duties, cæteris paribus, and lesser duties unto greater: the sabbath is made for man, and not man for the sabbath.

Luke vi. 5; xiii. 15; Mark ii. 27.