De 16:11
for this day is holy unto our Lord: neither be you sorry; confirming what the Levites had said and exhorted to, Ne 8:9
for the joy of the Lord is your strength; to rejoice, as the Lord commanded them on such days as these, was a means both of increasing their bodily strength and their inward strength, and of fitting them the more to perform their duty to God and men with cheerfulness, which sorrow and heaviness made unfit for; and the joy which has the Lord for its object, and comes from him, is the cause of renewing spiritual strength, so as to run and not be weary, walk and not faint, in the ways of God.