This text comes from The Complete Poetical Works of John Greenleaf Whittier, a historical songbook transcribed on Wikisource and reproduced from the pinned revision linked below.
Beside that milestone where the level sun,
Nigh unto setting, sheds his last, low rays
On word and work irrevocably done,
Life’s blending threads of good and ill outspun,
I hear, O friends! your words of cheer and praise,
Half doubtful if myself or otherwise,
Like him who, in the old Arabian joke,
A beggar slept and crownëd Caliph woke.
Thanks not the less. With not unglad surprise
I see my life-work through your partial eyes;
Assured, in giving to my home-taught songs
A higher value than of right belongs,
You do but read between the written lines
The finer grace of unfulfilled designs.