It is not always easy to trace the connexion between the several verses; at least not beyond the several divisions of the Psalm. Probably nothing more was intended, than the record of the exercises of his own heart at different periods, and under different circumstances. If, however, they are not links on the same chain, in continuous and unbroken dependence; they may at least be considered as pearls upon one string, of equal, though independent, value.
In praise of Psalm 119:
Jonathan Edwards, A Treatise Concerning Religious Affections, pp. 201-202:
I know of no part of the holy scriptures, where the nature and evidences of true and sincere godliness are so much of set purpose and so fully and largely insisted on and delineated, as the 119th Psalm; the psalmist declares his design in the first verses of the Psalm, and he keeps his eye on this design all along, and pursues it to the end. But in this Psalm the excellency of holiness is represented as the immediate object of a spiritual taste, relish, appetite, and delight of God's law, that grand expression and emanation of the holiness of God's nature, and prescription of holiness to the creature, is all along represented as the food and entertainment, and as the great object of the love, the appetite, the complacence and rejoicing of the gracious nature, which prizes God's commandments above gold, yea, the finest gold, and to which they are sweeter than the honey and honey comb; and that upon account of their holiness, as I observed before.
David Dickson, A Commentary on the Psalms, p. 342:
...in this psalm, as in a bundle, [David] hath collected the sum of his holy meditations, and of the profitable uses which he made of the revealed will of God in Scripture, in all the conditions wherein he was, to teach all the faithful after him, to have the word of God in special regard, and to have respect to it, as the only rule whereby they might find direction, consolation, and salvation, however matters went. To this end, for memory's sake, he hath filled the Hebrew alphabet with twenty-two meditations, every one of them beginning with a several letter of the alphabet, and every section having eight verses, beginning with the same letter, and every verse almost of every section under some expression, making mention of the Scripture.
William Binnie, The Psalms: Their History, Teachings and Use, p. 145:
Its two-and-twenty clusters yield the wine of the kingdom as copiously as any to be found in the Bible.
Bishop William Cowper, A holy alphabet for Sion's scholars: ... delivered by way of commentary upon the whole 119 Psalme (1613):
[Psalm 119 is a] holy alphabet, so plain that children may understand it -- so rich and instructive that the wisest and most experienced may learn something from it.
Edmund Calamy the Elder, The Godly Man's Ark, pp. 1-2:
This psalm, out of which my text is taken, exceeds all the other psalms, not only in length, but in excellency, so far, in the judgment of Ambrose, as the light of the sun excels the light of the moon. As the Book of Psalms is styled by Luther an epitome of the Bible, or, a little Bible; so may this psalm fitly be called an epitome of the Book of Psalms. It was written, as is thought, by David in the days of his banishment under Saul; but so penned, that the words thereof suit the condition of all saints. It is a public storehouse of heavenly doctrines, distributing fit and convenient instructions to all the people of God; and therefore should be in no less account with those who are spiritually alive, than is the use of the sun, air, and fire with those who are naturally alive. It is divided into two-and-twenty sections, according to the Hebrew alphabet, and therefore fitly called a holy alphabet for Zion's scholars, the ABC of godliness. Sextus Senensis calls it an alphabetical poem. The Jews are said to teach it their little children the first thing they learn, and therein they take a very right course, both in regard of the heavenly matter, and plain style fitted for all capacities. The chief scope of it is to set out the glorious excellences and perfections of the law of God.
Matthew Henry, The Life of Philip Henry, p. 133:
Once, pressing the study of the scriptures, he advised to take a verse of Psalm cxix. every morning to meditate upon, and so go over the psalm twice in the year; and that, saith he, will bring you to be in love with all the rest of the scripture; and he often said; -- all grace grows, as love to the word of God grows.
John Ker, The Psalms in History and Biography, p. 145:
[This Psalm] drew the special admiration of [Blaise] Pascal, who, as his sister Madame Perier says, often spoke with such feeling about it, 'that he seemed transported,' 'qu'il paraissait hors de lui même.' He used to say that, 'with the deep study of life, it contained the sum of all the Christian virtues.' He singled out ver. 59, as giving the turning-point of man's character and destiny: 'I thought on my ways, and turned my feet unto thy testimonies.'
Franz Delitzsch, Biblical Commentary on the Psalms, Vol. 3, p. 243:
In our German version it has the appropriate inscription, "The Christian's golden A B C of the praise, love, power, and use of the word of God;" for here we have set forth in inexhaustible fulness what the word of God is to a man, and how a man is to behave himself in relation to it.
Johannes Paulus Palanterius, Illustris Psalmorum Davidicorum (1600):
This psalm is called the Alphabet of Divine Love, the Paradise of all the Doctrines, the Storehouse of the Holy Spirit, the School of Truth, also the deep mystery of the Scriptures, where the whole moral discipline of all the virtues shines brightly. And as all moral instruction is delightsome, therefore this psalm, because excelling in this kind of instruction, should be called delightsome, inasmuch as it surpasses the rest. The other psalms, truly, as lesser stars shine somewhat ; but this burns with the meridian heat of its full brightness, and is wholly, resplendent with moral loveliness.
Charles H. Spurgeon, The Treasury of David, Vol. 6, pp. v-vi:
This marvellous poem seemed to me a great sea of holy teaching, moving, in its many verses, wave upon wave; altogether without an island of special and remarkable statement to break it up....Other psalms have been mere lakes, but this is the main ocean....This great Psalm is a book in itself: instead of being one among many psalms, it is worthy to be set forth by itself as a poem of surpassing excellence.
Martin Luther, Preface to the 1539 Wittenberg edition of Dr. Martin Luther's Works:
Moreover, I want to point out to you a correct way of studying theology, for I have had practice in this. If you keep to it, you will become so learned that you yourself could (if it were necessary) write books just as good as those of the fathers and councils, even as I (in God) dare to presume and boast, without arrogance and lying, that in the matter of writing books I do not stand much behind some of the fathers. Of my life I can by no means make the same boast. This is the way taught by holy King David (and doubtlessly used also by all the patriarchs and prophets) in the one hundred [nineteenth] Psalm. There you will find three rules, amply presented throughout the whole Psalm. They are Oratio, Meditatio, Tentatio.