This text comes from The Poetical Works of Robert Burns, a historical songbook transcribed on Wikisource and reproduced from the pinned revision linked below.
Wae worth thy power, thou cursed leaf!
Fell source o' a' my woe and grief!
For lack o' thee I've lost my lass!
For lack o' thee I scrimp my glass.
I see the children of affliction
Unaided, thro' thy curs'd restriction.
I've seen the oppressor's cruel smile,
Amid his hapless victim's spoil.
For lack o' thee I leave this much-lov'd shore,
Never, perhaps, to greet old Scotland more.