Singing the Sweetest Meditation

The 1650 Scottish Metrical Psalter, Psalm 119.103:

How sweet unto my taste, O Lord,
are all thy words of truth!
Yea, I do find them sweeter far
than honey to my mouth.

John Lightfoot, "A Sermon Preached at St. Mary's, Cambridge, June 24, 1660 on 1 Cor. xiv. 26," in John Lightfoot, Sermons: And Sermon-Notes, pp. 36-37:

Many things are spoken of the excellency of the Book of Psalms; and many may be spoken of the excellency of singing psalms. I may allude to that expression, "Many daughters have done virtuously, but thou excellest them all:" so may I say in reference to this duty, 'All duties are excellent, but this includes all.' In singing of psalms, there is what is in other services, and more. Prayer is our duty, -- praise, speaking of God's works, singing, are our duties, -- but this last is all; it like the holy incense, mixed of all these perfumes.
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As God requires outward and inward worship, so a spiritual frame for inward worship may be forwarded by outward composure. Gazing drowsiness hinders the activity of the soul, but the contrary temper fathers and helps it. Singing calls up the soul into such a posture, and doth, as it were, awaken it: it is a lively rousing up of the heart.
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This is a work of the most meditation of any we perform in public. It keeps the heart longest upon the thing spoken. Prayer and hearing pass quick from one sentence to another; this sticks long upon it. Meditation must follow after hearing the word, and praying with the minister; for new sentences, still succeeding, give not liberty, in the instant, well to muse and consider upon what is spoken: but in this, you pray and meditate, praise and meditate, speak of the things of God and meditate. God hath so ordered this duty, that, while we are employed in it, we feed, and chew the cud together. 'Higgaion,' or 'meditation,' is set upon some passages of the Psalms, as Psal. ix. 16. The same may be writ upon the whole duty, and all parts of it, -- viz. 'meditation.' Set before you one in the posture to sing to the best advantage: eyes, lifted up to heaven, denote his desire, that his heart may be there too: he hath before him a line or verse of prayer, mourning, praise, mention of God's works; how fairly now may his heart spread itself in meditation on the things, while he is singing it over! Our singing is measured in deliberate time, not more for music than meditation. He that seeks not, finds not, this advantage in singing psalms, -- hath not yet learned what it means.