Article 1641 of the French Civil Code

The seller is liable for any hidden defects in the item sold which render it unfit for its intended use, or which impair that use to such an extent that the buyer would not have purchased it, or would only have paid a lower price for it, had he been aware of them.

Original in French

Article 1641

Le vendeur est tenu de la garantie à raison des défauts cachés de la chose vendue qui la rendent impropre à l’usage auquel on la destine, ou qui diminuent tellement cet usage que l’acheteur ne l’aurait pas acquise, ou n’en aurait donné qu’un moindre prix, s’il les avait connus.