Grace breeds delight in God, and delight breeds meditation. A duty wherein consists the essentials of religion, and which nourisheth the very life-blood of it; and that the Psalmist may shew how much the godly man is habituated and inured to this blessed work of meditation, he subjoins, ‘In his law doth he meditate day and night; not but that there may be sometimes intermission: God allows time for our calling, he grants some relaxation; but when it is said, the godly man meditates day and night, the meaning is, frequently: he is much conversant in the duty. It is a command of God to pray without ceasing, 1 Thess. 5:17. The meaning is, not that we should be always praying, as the Eutiches held, but that we should every day set some time apart for prayer: so Drusius and others interpret it. We read in the Old law it was called the continual sacrifice, Numb. 28:24 not that the people of Israel did nothing else but sacrifice, but because they had their stated hours, every morning and evening they offered, therefore it was called the continual sacrifice: thus the godly man is said to meditate day and night, that is, he is often at this work, he is no stranger to meditation.
Doct. The proposition that results out of the text is this, That a good christian is a meditating christian, Ps. 119:15. ‘I will meditate in thy precepts.’ 1 Tim. 4:15. ‘Meditate upon these things.’ Meditation is the chewing upon the truths we have heard: The beasts in the old law that did not chew the cud, were unclean: the christian that doth not by meditation chew the cud, is to be accounted unclean. Meditation is like the watering of the seed, it makes the fruits of grace to flourish.

Watson, T. (1829). A Christian on the Mount, or a Treatise concerning Meditation. In Discourses on Important and Interesting Subjects, Being the Select Works of the Rev. Thomas Watson (Vol. 1, pp. 197–198). Edinburgh; Glasgow: Blackie, Fullarton, & Co.; A. Fullarton & Co.