The Book of Psalms is canonical in Judaism (Ketuvim) and Christianity (Old Testament), with its authority confirmed by ancient manuscripts (Qumran), the New Testament, and councils (Hippo, Carthage). The Ethiopian Orthodox Tewahedo Church, however, has a broader canon that includes Psalm 151 as an integral part of the Psalter, accepted as Holy Scripture also by Orthodox, Syriac, and Armenian traditions, demonstrating the historical diversity of biblical canons.
Psalms
Chapter 1 — Book One (Psalms 1-41)
Blessed is the man that walketh not in the counsel of the ungodly, nor standeth in the way of sinners, nor sitteth in the seat of the scornful.
But his delight is in the law of the LORD; and in his law doth he meditate day and night.
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.
The ungodly are not so: but are like the chaff which the wind driveth away.
Therefore the ungodly shall not stand in the judgment, nor sinners in the congregation of the righteous.
For the LORD knoweth the way of the righteous: but the way of the ungodly shall perish.