The Psalm 'outside the number'

Holy Transfiguration Monastery

My recent post about the Qumran tradition of Davidic authorship is a reminder that not all of the psalm literature of the ancient Israelites made into the canonical Psalter we know from our bibles. In the Orthodox tradition, we find an extra psalm in some manuscripts of the Greek Septuagint which is described as "outside the number" (εξωθεν του αριθμου) of the 150 Psalms. It is sometimes referred to as Psalm 151 and is labelled thus in the New Oxford Annotated Bible. Here it is in the New Revised Standard Version:

This psalm is ascribed to David as his own composition (though it is outside the number), after he had fought in single combat with Goliath.

1    I was small among my brothers,
and the youngest in my father’s house;
I tended my father’s sheep.
2    My hands made a harp;
my fingers fashioned a lyre.
3    And who will tell my Lord?
The Lord himself; it is he who hears.
4    It was he who sent his messenger
and took me from my father’s sheep,
and anointed me with his anointing oil.
5    My brothers were handsome and tall,
but the Lord was not pleased with them.
6    I went out to meet the Philistine,
and he cursed me by his idols.
7    But I drew his own sword;
I beheaded him, and took away disgrace from the people of Israel.

As far as I know, no one has attempted to set this to metred verse, but it is included in Saint Dunstan's Plainsong Psalter with an appropriate chant tone.