“For in the days we know not of
Did fate begin
Weaving the web of days that wove
Your doom.”

The London Literary Gazette, 1824

Robert M. Price, in The Psychology of Biblicism http://www.robertmprice.mindvendor.com/art_biblicism.htm, a modification of the quote from Sir Walter Scott

Canto VI, st. 17.
Variant: Oh what a tangled web we weave when first we practice to deceive
Source: Marmion (1808)

As quoted in The Way To Win : Showing How To Succeed In Life (1887) by John Thomas Dale, p. 89
Context: I record the conviction that in one way or another, special individual help is given to every creature to endure to the end. It has been my own experience, that always when suffering, whether mental or bodily, approached the point where further endurance appeared impossible, the pulse of it began to ebb and a lull ensued.
You are tender-hearted, and you want to be true, and are trying to be; learn these two things: Never be discouraged because good things get on so slowly here; and never fail daily to do that good which lies next to your hand. Do not be in a hurry, but be diligent. Enter into the sublime patience of the Lord. Trust to God to weave your little thread into the great web, though the pattern shows it not yet. When God's people are able and willing thus to labor and wait, remember that one day is with the Lord as a thousand years, and a thousand years as one day; the grand harvest of the ages shall come to its reaping, and the day shall broaden itself to a thousand years, and the thousand years shall show themselves as a perfect and finished day.

Misattributed

“Ode,” Complete Works (1883), vol. 9, p. 73

Poems by Currer, Ellis, and Acton Bell (1846), From Retrospection (1835)

As quoted in Graded Selections for Memorizing : Adapted for Use at Home and in School (1880) by John Bradley Peaslee, p. 104

Song lyrics, Amarantine (2005)