Idleness is a moth or canker of the mind, and the fruits thereof are wicked cogitations, evil affections, and worse actions; corrupt trees without fruit, twice dead and plucked up by the roots, engendering in the mind a loathing of God and godliness.
The heart must be kept courageous and strong and lively, like an instrument which is tuned to tune all the rest, or else every grief will make thee impatient. In Deuteronomy 30:9 it is said that God rejoices to do us good, and therefore in Deuteronomy 28 the Jews are reproved because they rejoiced not in the service of God. As He loveth a cheerful giver, so He loveth a cheerful server and a cheerful preacher and a cheerful hearer and a cheerful worshiper; and therefore David saith, "Let us sing unto the LORD" (Ps. 95:1), showing, as it were, the tune which delights God's ears. Sermons, 115