CLÉANTE: And just as there is nothing I more revere
Than a soul whose faith is steadfast and sincere,
Nothing that I more cherish and admire
Than honest zeal and true religious fire,
So there is nothing that I find more base
Than specious piety’s dishonest face.

[Et, comme je ne vois nul genre de héros
Qui soient plus à priser que les parfaits dévots,
Aucune chose au monde et plus noble et plus belle
Que la sainte ferveur d’un véritable zèle,
Aussi ne vois-je rien qui soit plus odieux
Que le dehors plâtré d’un zèle spécieux.]

Molière (1622–1673) French playwright, actor [stage name for Jean-Baptiste Poquelin]

Tartuffe, or the Hypocrite [Le Tartuffe, ou L’Imposteur], Act 1, sc. 6 (1669) [tr. Wilbur (1963), 1.5]
    (Source)

The references to plaster, whitewashing, etc., come from the Bible, Matthew 23:27-28, condemning hypocrisy.

(Source (French)). Other translations:

And as I see no Character in Life more great or valuable than to be truly devout, nor any thing more noble, or more beautiful, than the Fervor of a sincere Piety; so I think nothing more abominable than the outside Daubing of a pretended Zeal.
[tr. Clitandre (1672)]

And as I know no character more worthy of esteem than the truly devout, nor anything in the world more noble or beautiful than the holy fervour of sincere piety, so I know nothing more odious than the whited sepulchre of a pretended zealot, than those downright imposters, those devotees for public show.
[tr. Van Laun (1876)]

And as I know nothing in the world so noble and so beautiful as the holy fervour of genuine piety, so there is nothing, I think, so odious as the whitewashed outside of a specious zeal.
[tr. Wall (1879)]

And as I see nothing in life more noble or beautiful than the fervour of sincere piety, so I think nothing more odious than the plastered exterior of a false zeal.
[tr. Mathew (1890)]

And since I do not know any character more admirable than the truly devout, nor anything in the world more noble and more beautiful than the righteous fervor of a sincere piety, neither do I know anything more odious than the whited sepulchre of a specious zeal.
[tr. Waller (1903)]

And as I find no kind of hero more
To be admired than men of true religion,
Nothing more noble or more beautiful
Than is the holy zeal of true devoutness;
Just so I think there's naught more odious
Than whited sepulchres of outward unction.
[tr. Page (1909)]

And as I see no kind of character
More honorable than true devotion is,
Nothing more noble and more beautiful
Than fervent, genuine, holy piety,
So I find nothing on earth more odious
Than the false show of whited sepulchres.
[tr. Bishop (1957)]

And, as there are no heroes I revere
More than those whose devoutness is sincere,
And nothing worthier of veneration
Than genuine religious dedication,
So, nothing seems more odious to me
Than the disguise of specious piety.
[tr. Frame (1967)]

What jewel more precious can there be
Than perfect, unfeigned piety,
A fervour that is felt, and real?
But this ... this squashed flea kind of zeal,
Worn, as a lady wears her paint,
The posturing of the plaster saint,
This, above all things, I deplore.
Nothing on earth disgusts me more.
[tr. Bolt (2002)]

I don’t know any heroes more worthy of respect than the truly pious or anything more noble and beautiful than holy passion and saintly zeal. And I don’t know anything more hateful than those whited sepulchres, the phony zealots.
[tr. Steiner (2008)]