E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
A corruption of quatuor tempora, through the Dutch quatemper and German quatember. The four times are after Quadragesima Sunday, Whit Sunday, Holyrood Day (September), and St. Lucias Day (December). The supposition that persons sat in embers (or ashes) on these days is without foundation.