This text comes from The Book of Scottish Song, edited by Alexander Whitelaw, a historical songbook transcribed on Wikisource and reproduced from the pinned revision linked below.
I canna sleep a wink, lassie,
Whan I gang to bed at night,
But still o' thee I think, lassie,
Till morning sheds its light.
I lie and think o' thee, lassie,
And I toss frae side to side,
Like a vessel on the sea, lassie,
When stormy is the tide.
My heart is no my ain, lassie,
It winna bide wi' me,
Like a birdie it has gane, lassie,
To nestle saft wi' thee.
I canna lure it back, lassie,
Sae keep it to yoursel',
But, oh! it sure will brak, lassie,
If you dinna use it well.
Whare the treasure is, they say, lassie,
The spirit lingers there,
And mine has fled away, lassie,
You needna ask me where:
I marvel oft if rest, lassie,
On my eyes and heart wad bide,
If I thy troth possess'd, lassie,
And thou wert at my side.