Let them sing, they will have to pay.
Ils chantent, ils payeront.
Original text (French)
Source, in full
Saying uttered when the populace, incensed by some new form of extortion, vented their anger against the Minister in Mazarinades. — Edouard Fournier, L'Esprit dans l'histoire, 5th ed. (1883), p. 267. — King (1904), no. 1321
Notes from Wikiquote
Cf. Alexandre Dumas, Vingt ans après (1845), ch. 2; Arsène Houssaye, Voyages Humoristiques—Amsterdam—Paris—Venise (1856), translated in Bentley's Miscellany, vol. xli (1857), p. 258; Samuel Adams Drake, Around the Hub: A Boys' Book about Boston (1881), p. 199; variant reported by the Marquis de Gabriac, Souvenirs diplomatiques de Russie et d’Allemagne (Revue des Deux Mondes, 1896), pt. 3, p. 590: Qu’ils chantent, pourvu qu’ils payent.