Why should he toil and moil, and be at so much trouble to pick himself up out the mud, when, in a little while hence, the strong arm of his Uncle will raise and support him?
-- Nathaniel Hawthorne, The Scarlet Letter
He saw himself in the sleepless moil of early parenthood, and felt a plunging anxiety.
-- Alan Hollinghurst, The Spell
Moil comes from Middle English moillen, "to soak, to wet," hence "to soil, to soil one's hands, to work very hard," from Old French moillier, "to soften, especially by making wet," ultimately from Latin mollis, "soft."