"Sinners in the Hands of an Angry God" by Jonathan Edwards, a Puritan minister, is arguably the most famous sermon in American literature. It was delivered in 1741 at the peak of a revival of spirituality in America called the Great Awakening to a rather recalcitrant church. The sermon is full of vivid imagery designed to awaken fear and inspire faith in listeners, and by most accounts, it worked.
In the fourth point of the "Application" section of the sermon, Edwards reminds the people sitting in the pews--many of whom by this point in the sermon are crying in the aisles as they recognize their desire for salvation--how long they will suffer the tortures of hell [bold added]:
It is everlasting wrath. It would be dreadful to suffer this fierceness and wrath of Almighty God one moment; but you must suffer it to all eternity. There will be no end to this exquisite horrible misery. When you look forward, you shall see a long forever, a boundless duration before you, which will swallow up your thoughts, and amaze your soul; and you will absolutely despair of ever having any deliverance, any end, any mitigation, any rest at all. You will know certainly that you must wear out long ages, millions of millions of ages, in wrestling and conflicting with this almighty merciless vengeance; and then when you have so done, when so many ages have actually been spent by you in this manner, you will know that all is but a point to what remains.
Note Edwards's repetition of his theme in this sentence: "you will absolutely despair of ever having any deliverance, any end, any mitigation, any rest at all."
According to this sermon, the "damned will suffer in hell" forever and ever, and then some more.