Psalm 1
1 Blessed is the man who doesn’t walk in the counsel of the wicked, nor stand on the path of sinners, nor sit in the seat of scoffers;
2 but his delight is in Yahweh’s law. On his law he meditates day and night.
3 He will be like a tree planted by the streams of water, that produces its fruit in its season, whose leaf also does not wither. Whatever he does shall prosper.
World English Bible (WEB)
On Psalm 1: the meaning of the poem that opens the whole book of Psalms, the image of "a tree planted by the streams of water" and why it is seen as an introduction.
Psalm 1 is the doorway to the book of Psalms; it stands like an introduction to the hundred and fifty poems that follow. It begins by comparing two ways: a life that listens to wisdom and a life that turns from it.
The psalm likens the person rooted in wisdom to "a tree planted by the streams of water, that produces its fruit in its season." This plain image turns the difference between what lasts and what passes into a picture that stays in the mind.
You can move to the chapter below to read the whole psalm and see how the two ways are compared. The related collection on wisdom bridges to other verses on the same theme.