I don't have sheet music but I gleaned these lyrics from this recording.
https://www.youtube.com/watch?v=QHY3LJ8eZKE
I'm sure I got several of the lyrics wrong so please correct

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All alone and in captivity we’ve met the enemy
They wilt as they recalled the joys of home
And as they sat in the midst of scorn and shame
They heard them mock their Father’s name
Then they required of them Zion’s song

In a lost and a lone society heartaches steal my melody
And I tend to say why should I sing His song
But as the angels voice their melody ? from you and me
And as for me the breeze has played my harp too long

I’ve got my harp out of the willow
And I’m singing songs of Zion
I’ve heard the wind blow through the strings too long;
Though I may never, ever understand
Why I must sing in this strangers land,
But just to praise you Lord I’ll sing Your song

Is there anybody that has the sheet music or lyrics to “Willow Tree”? It was sung by the speers. Please and thank you.