The reason Psalm 119 has 176 verses is that the Hebrew alphabet has 22 letters. The psalmist exults in the multifaceted preciousness of God’s word by taking each letter of the alphabet and writing eight verses of exultation, each verse beginning with that letter. It’s like saying: “The word of God is precious in every way from A to Z—beyond perfection.” (Eight is one more than seven, the number of completeness and perfection.)
Ordinarily in each group of eight verses, the psalmist uses mostly different words that start with the letter for that section of the acrostic. For example, the verses beginning with the letter heth (verses 57–64) use eight different words beginning with that letter. But verses 65-72, that start with the Hebrew letter teth, stand out, because they begin with the same word five times—the word good (tov). This makes us sit up and take notice.
Something really good is being emphasized. What is the good he wants us to see?
Here is my translation in awkward English that lets you see the prominence of the word good.
65: Good (tov) you did, Yahweh, with your servant according to your word.
66: Good (tov) discernment and knowledge, teach me, because in your commandments I trust.
67: Before I was afflicted I erred, but now I keep your word.
68: Good (tov) you are and you cause good to happen, teach me your statutes.
69: Smear upon me lies, so do the proud, but I with all my heart watch your precepts.
70: Gross like fat is their heart, I delight in your instruction.
71: Good for me (tov li) it was that I was afflicted, so that I might learn your statutes.
72: Good for me (tov li) the instruction of your mouth, more than thousands of gold and silver pieces.
These are not random comments about what is good. They are connected. And a specific good is in mind.
Verse 65 says that God did something good. It accords with his word. That means God’s word is designed for our good and that what God does to help us go deep with his word is good. What did he do that makes the psalmist write this?
In verse 66 the psalmist prays that God would give him good discernment because he trusts in God’s commandments. That means God does not bless with discernment a negative attitude toward his word. If we trust that his words are the best counsel in the world, he will give us discernment when we ask.
So the psalmist pleads for a mind and heart that penetrates deep into the word of God and becomes spiritually discerning for all the hundreds of situations that are not addressed directly by the Bible. So, he prays—and we should pray—God, do whatever you must do to teach me your word.
Verse 67 tells us what God did to answer this prayer for biblical discernment: “Before I was afflicted I erred, but now I keep your word.” God sent affliction. And this affliction was a profound teacher. It moved the psalmist into deeper obedience (“Now I keep your word”).
But not only obedience, also understanding. Verse 71: “Good it was for me that I was afflicted, so that I might learn your statutes.” Affliction brought learning. This is the discernment he had prayed for.
So the good that God did (v. 65) was Bible-illumining, discernment-giving, obedience-producing affliction. What was the affliction? It was slander from spiritually hardened adversaries. Verses 69: “The proud smear me with lies, but I with all my heart watch your precepts.”
This is the good the psalmist wants us to see. Verse 68: “Good you are, and you cause good to happen.” The good is the affliction that brings about understanding, discernment, and obedience. “Good it was for me that I was afflicted, so that I might learn your statutes” (v. 71).
How can he call affliction good? It’s because in his value-scheme, penetrating insight into God’s word is more valuable that thousands of gold and silver pieces.
Verse 72: “Good to me is the instruction of your mouth more than thousands of gold and silver pieces.” If God and his word are your highest values—your greatest desires—then whatever helps you know them and experience them deeply will be good—not easy, and maybe not even morally right (like slander from your adversaries), but good in the sense that God ordains it to give you what is absolutely best—the illumining effect of God’s infinitely valuable word.
In Martin Luther’s meditation on these verses he said that trials (Anfectungen) were one of his best teachers:
I want you to know how to study theology in the right way. I have practiced this method myself.... Here you will find three rules. They are frequently proposed throughout Psalm  and run thus: Oratio, meditatio, tentatio (Prayer, meditation, trial).... [Trials] teach you not only to know and understand but also to experience how right, how true, how sweet, how lovely, how mighty, how comforting God’s word is: it is wisdom supreme.
As soon as God’s Word becomes known through you, the devil will afflict you... and will teach you by his temptations to seek and to love God’s Word. For I myself... owe my papists many thanks for so beating, pressing, and frightening me through the devil’s raging that they have turned me into a fairly good theologian, driving me to a goal I should never have reached. (What Luther Says: An Anthology, 1359–1360)
Lord, incline our hearts to your word and not to gold and silver. Make us cherish your word so much that we embrace whatever it takes to give us understanding and good discernment and faithful obedience.
And when it comes, give us the grace to say, “Good you are, and you cause good to happen.”