Never complain and never explain.

Benjamin Disraeli (1804-1881) English politician and author

(Attributed)
    (Source)

Most often cited to John Morley, Life of William Ewart Gladstone, Vol. 1, Book 2, ch. 2, sec. 1 (1903). This was Disraeli's distillation of advice that Lord High Chancellor John Copley, Lord Lyndhurst, gave at a January 1835 dinner attended both a young Gladstone and Disraeli:

Never defend yourself before a popular assemblage, except with and by retorting the attack; the hearers, in the pleasure which the assault gives them, will forget the previous charge.

The phrase is also attributed to Benjamin Jowett, Henry Ford II, and Charles Stewart Parnell.