MIDRASH TEHILLIM
1.....(1.10)
He is like a tree that has been planted beside streams of water
God lifted Adam up and planted Him in the Garden of Eden. That brings fruits in its season. Adam brought forth Cain. His leave will not wither. Abel will not wither. Seth will prosper. Not so the wicked (the Serpent)
God gave three good gifts to Israel - mercy, modesty and loving kindness.
If a man has no modesty, his forebears did not stand on Mount Sinai.
2.....(1.11)
He is like a tree that has been planted...
The word PLANTED is not used here, the word denoting - FIXED FIRMLY is used instead. telling you that even if all the winds come and blow at the righteous man, they will be unable to budge him from his place.
3.....(1.12)
blessed is the man (who speaks about Noah)...
It is written - Noah was a righteous man (Bereshit/Genesis 6:9). He didn't walk in the councel of the wicked. That is the wicked of three generations: the generation of Enosh (wicked), the generation of the flood (sinners), the generation of the dispersion of the races of men (scorners).
His delight is in the Torah of the Lord. That is in the seventh commandments [commanded the sons of Noah].
And he will be like a tree planted securely in rivers of water. That God set Noah securely in the ark.
...his fruit in his seasons. Noah was five hundred years old before he begot sons - Shem, Ham and Japheth.
4.....(1.13)
blessed is the man...
That is Avraham, of whom God said - He is a prophet (Bereshit/Genesis 20:7).
The man that walks not in the counsel of the wicked. Avraham did not walk in the counsel of the generation which decided to build the tower.
Nor stand in the way of sinners. That is Avraham, stood not with the men of Sodom.
Nor sit in the seat of the scornful, meaning men like Abimelech, who offered land to Avraham, but Avraham would not settle on that land, for his delight was in the Torah of the Lord.
And will be like a tree that is planted by the rivers of water. God lifted Avraham up and planted him in the Garden of Eden. This verse can be also interpreted as - God planted Avraham in the Land of Israel.
That brings forth his fruit in his time. That is Ishmael, Isaac and children of Keturah, their leaf wil not wither. Not so for the wicked, this is Nimrod and his friends.
5.....(1.14)
...another word of blessed is the man...
Tribe of Levi walked not in the counsel of the generation of the wilderness.
Not stood in the way of sinners (who made the golden calf).
Not sit in the seat of the scornful, who celebrated after making the golden calf.
God planted the tribe of Levi in the Land of Israel, the entire tribe entered the Land.
6.....(1.19)
And he will be like a tree...
Wisdom of Torah is likened to the tree of life in the Garden of Eden, because it is as precious as life itself to all living things.