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 121 — A Song of degrees.
I will lift up mine eyes unto the hills, from whence cometh my help.
My help cometh from the LORD, which made heaven and earth.
He will not suffer thy foot to be moved: he that keepeth thee will not slumber.
Behold, he that keepeth Israel shall neither slumber nor sleep.
The LORD is thy keeper: the LORD is thy shade upon thy right hand.
The sun shall not smite thee by day, nor the moon by night.
The LORD shall preserve thee from all evil: he shall preserve thy soul.
The LORD shall preserve thy going out and thy coming in from this time forth, and even for evermore.