The following quotation is from Richard Phillips’ expository commentary on the book of Hebrews:

Complaining is a symptom of a deeper spiritual problem. If we grumble and complain, if we rebel and revolt, it indicates a very poor knowledge of God. Indeed, this was exactly the Lord’s diagnosis of Israel, as we see in verse 10: “They always go astray in their heart; they have not known my ways.” This was the same complaint God made through the prophet Isaiah: “The ox knows its owner, and the donkey its master’s crib, but Israel does not know, my people do not understand” (Isa. 1:3).

How remarkable that these Israelites did not know God after all they had seen and heard and received from his hand! How could they not have known his ways! The point is that while they had enjoyed God’s works, they had not reflected on him. They were interested in what God did for them, but not in God himself. We are reminded of Jesus’ great prayer to the Father in John 17, where our Lord said, “This is eternal life, that they know you the only true God, and Jesus Christ whom you have sent” (John 17:3). Salvation is not a matter of knowing God’s blessings–after all, many people who do not know God know his blessings–but it is a matter of knowing him, understand his character and his ways, and more and more trusting him in all things.

If you are not growing in your knowledge of God, your understanding and appreciation of his ways, let this be a warning to you. We are to be students of God’s character, learning what God is like through the circumstances of our lives and especially through the Bible, and growing in our love for him. How is God manifesting his power and grace? Can we look back and discern his once-hidden wisdom, his goodness, his patience, his holiness and love? This is the way to worship him, and indeed, the way to keep our sinful hearts from hardening.

Let me put it another way. What should you be looking for when you read your Bible? There is nothing more important than for you to study God himself. “What does this Scripture tell me about God, about his character, and about his ways?” “How can I know him better and trust him more?” The study of the attributes of God is one of the most vital of all subjects, for to know God is to trust him and to worship him with both awe and gratitude. Charles Spurgeon was right when he said of the study of God: “It is a subject so vast, that all our thoughts are lost in its immensity; so deep, that our pride is drowned in its infinity… But while the subject humbles the mind, it also expands it. Nothing will so enlarge the intellect, nothing so magnify the whole soul of man, as a devout, earnest, continuing investigation of the great subject of the Deity.”

When God is filling our thoughts, we learn to rejoice even in our trials. Indeed, we discern that trials are given to draw us nearer to him. Donald Grey Barnhouse observed this, saying: “How wonderful that when we are blinded by tears, we can nevertheless see our God. In fact, our tears become crystal lenses through which He is magnified; and in the midst of suffering we realize the greatness of His power and the tenderness of His love.”

If you want the gifts while having no real interest in the Giver, then you will not persevere through the trials of this life, when circumstances turn against you and God’s blessings are seen only with eyes of faith. If you resent the challenges God sends, then when the hot sun beats upon your back, when your throat becomes dry and weary, what was said of those ancient Israelites will be said of you as well: “They always go astray in their heart; they have not known my ways… They shall not enter my rest” (Heb. 3:10-11).

Israel complained all through their forty years in the desert, never learning God’s ways despite mercy after mercy. Over and again they complained and rebelled about the same old things. All the while God’s pillar of fire guided them, the manna fell from heaven, water came forth from the rock, and even their clothes and shoes did not wear out as the Lord cared for them. Still, as the writer of Hebrews summarizes in verses 9-11: “Your provoked with that generation, and said, ‘They always go astray in their heart; they have not know my ways.’ As I swore in my wrath, ‘They shall not enter my rest.'”

We are well advised, therefore, to heed the exhortation with which our passage concludes: “Take care, brothers, lest there be in any of you an evil, unbelieving heart, leading you to fall away from the living God.”