Proverbs 16:9 - God Is Sovereign

In his heart a man plans his course, but the LORD determines his steps.
Prov 16:9 (NIV)

The topic of these verses is God and His ultimate control over human
activity. [Ryrie SB]

This is a magnificent expression of the sovereignty of God, whereby Yahweh
inevitably and without exception accomplishes His will and purpose through
free-willed agents acting freely but responsibly. Man must be a free agent
to be in the image of God, and God must be immutable, i.e., unchanging, in
order to be God (Mal. 3:6). Permitting or overruling the acts of man without
infringing upon his freedom or interrupting his responsibility (e.g., the
brothers of Joseph in Gen. 37:26-28; 45:5) is an awesome expression of God's
providence. [Believer's SB]

Everything that we do is done by the life that God lends us and therefore by
His permission. Man devises but does not know whether he will live to carry
out his plans. Obviously, in recognition of this truth some Christian people
adopted the custom of saying, "God willing," when they announced their
future plans (see James 4:13-15). [SDA Commentary]

As a reasonable creature, that has the faculty of contriving for himself:
His heart devises his way, designs an end, and projects ways and means
leading to that end, which the inferior creatures, who are governed by sense
and natural instinct, cannot do. The more shame for him if he do not devise
the way how to please God and provide for his everlasting state. But as a
depending creature, that is subject to the direction and dominion of his
Maker. If men devise their way, so as to make God's glory their end and his
will their rule, they may expect that he will direct their steps by his
Spirit and grace, so that they shall not miss their way nor come short of
their end. ( Matthew Henry's Commentary)

That God has an "eternal purpose" for all things is both scriptural and
logical. If God is God at all, He is sovereign. He cannot work independently
of His own nature, for then He would cease to be God, something that is
impossible. He is a wise God; therefore, His eternal purpose is a wise one.
He is a powerful God; therefore, He is able to accomplish what He purposes.
He is a loving God; therefore, what He purposes will manifest His love. He
is an unchanging God; therefore, His purpose is unchanging. . . . .
Words like "predestination" and "election" frighten some people and are
greatly misunderstood by others. "If God has an eternal purpose, then why
bother to do anything?" some people ask. "Why pray? Why send out
missionaries? After all, God will certainly achieve His purpose!"
But not without us! God has ordained (and this is amazing) that His purposes
shall be fulfilled in and through His church. Why pray? Because prayer is
one of God's ordained ways to accomplish His will in us and through us. Why
send out missionaries? Because He has commanded us to carry the gospel to
the ends of the earth, and our obedience is a part of His ordained plan.
God's eternal purpose, established "before the world was," is not an excuse
for carelessness and disobedience. It is one of our greatest encouragements
to obedience and service.
God's eternal purpose is not fatalism. Rather, it is the perfect plan of a
loving Father, and our Father loves us too much to harm us. He is too wise
to make mistakes. "The counsel of the Lord stands forever, the plans of His
heart from generation to generation" (Psalm 33:11). Note that important
phrase: "the plans of His heart...."
Please keep in mind that a part of God's eternal plan is the fact that man
shall have moral freedom. Divine sovereignty and human responsibility do not
conflict or contradict each other; they are friends, not enemies. . . .
"But why did God plan it this way?" some may ask. Because His plan is the
best. God cannot ordain less than the very best. There are some things about
God's plan that we may not understand, but we agree with our Lord's
affirmation of faith in Matthew 11:26, "Yes, Father, for thus it was
well-pleasing in Thy sight." And if any of us gets the idea that God needed
our help as consultants, we had better listen again to Paul: "For who has
known the mind of the Lord, or who became His counselor?" (Romans 11:34).
God did not need our help in framing His great plan, nor does He need our
criticism of it. But He does want to share with us the privilege of working
out His plan in this world. . . . . . .
These truths were not given so that we might debate, but that we might
surrender and worship. It is not a big head, but a burning heart, that
proves we have grasped something of the meaning of God's eternal plan.
[Prayer: Basic Training.by Warren W. Wiersbe]