This is the 26th riddle from The Exeter Book.
An enemy came, claiming my life.
My worldly strength he stripped, then wet me,
Drowned me in water then drew me out,
Set me in sunshine, where soon I lost
The hair I had. A hard edged knife
Cut me and ground me clean from all grime,
Fingers folded me, a fine bird's clothing
With swift drops made many traces
Across my brown skin's breadth, imbibing the tree-dye,
A valley stream strode across me
And left a dark path. A pious man clothed me
In boards, then hauled hide across me
Bedecked with gold; I was glad to be bound by
The smith's fine work of wire around me.
Now the decorations and the dye of red
In such wonderous forms give wider fame
To the people's protector from the pains of hell.
If the children of men choose to enjoy me
They shall be safer and surer of victory,
Mightier of heart, happier of mind,
Wiser of spirit, wealthier in friends
Who are dearer and faster, more faithful and better,
Kinder and fairer, who foster glory
With fondest love and fellowship,
Kindness links them, its loving embrace
Holding them soundly. Say what I am,
That is needful to man. My name is famous,
A giver of healing, and holy too.
Translation by Conrad Leviston.
Although some give the conservative anwer book, the answer is almost certainly The Bible. Note that the translation above was made on the assumption of the latter answer.