"And he shall be like a tree planted by the rivers of water, that bringeth forth his fruit in his season; his leaf also shall not wither; and whatsoever he doeth shall prosper." (Psalm 1:3)
The first psalm constitutes a contrast between the godly individual who delights in God's law and the ungodly person who is destined for destruction. "Blessed" literally means "happy," and the habits of such a happy one are described as not only avoiding the thought patterns and lifestyle of the ungodly (v. 1), but also delighting in and obeying the Word of God (v. 2). Our text describes four results of being blessed or happy in the biblical sense.
First, "he shall be like a tree planted by the rivers of water," with the implication being to dwell in a secure, bountiful state. The verb "plant" actually means "transplanted," now firmly rooted and provided for, no longer vulnerable, tentative, and undernourished.
Second, he "bringeth forth his fruit in his season." One does not so nourish a tree without any purpose. Here, following the analogy, the godly individual, nourished and protected by his Maker, can likewise expect to accomplish a purpose--in this case to bear spiritual, eternal fruit.
Third, "his leaf also shall not wither." Eternal life is the present possession of all who have been "transplanted" by the Lord. Such a one can expect to faithfully bring forth precious fruit in each season of his life.
Fourth, "whatsoever he doeth shall prosper." Success in each endeavor undertaken by one whose delight is the Lord can be expected, such success defined by that which brings spiritual maturity, and eternal fruit, and prosperity, as He defines prosperity.
"For the LORD knoweth the way of the righteous: but the way of the ungodly shall perish" (v. 6). JDM