John Wesley on Exodus 34:21

Here is a repetition of several appointments made before, especially relating to their solemn feasts: when they had made the calf they proclaimed a feast in honour of it; now, that they might never do so again, they are here charged with the observance of the feasts which God had instituted. Thou shalt rest, even in earing - time and in harvest - The most busy times of the year. All wordly business must give way to that holy rest: harvest - work will prosper the better for the religious observation of the sabbath - day in harvest - time. Hereby we must shew that we prefer our communion with God, before either the business or the joy of harvest.