Shalom Achim v'Achiot,

I hope you are all well, Im Yirtsah YHWH. I was wondering if anyone had insights to the "151st Psalm". Do you think it is Apocryphal or do you think it is legitimate?

Psalm (151)
This Psalm is ascribed to David and is outside the number. When he slew Goliath in single combat.
(This Title given in the Septuagint)

1 Little was I among my brethren:
A younger brother in my father's house.
2 My hands, they made an instrument of music:
My fingers, they prepared a psaltery.
3 And who shall bring back tidings to my master?
YHWH Himself, Himself gives ear.
4 Himself sent forth His messenger:
And took me from among my father's sheep;
And with the oil of His annointing He annointed me.
5 Comely my brethren were and tall:
And yet they found not favour with YHWH.
6 But I, I sallied forth to meet the alien:
And he reviled me by all his idols.
7 But I drew forth the sword that was beside him:
I cut his head off with it,
And from the sons of Israel removed reproach.