Lying is a villainous vice, and an ancient writer depicts it as most shameful when he says that to lie is to manifest contempt of God together with fear of man. It is not possible to represent more fully the horror, the vileness, the outrageousness of it. For what can be conceived more villainous than to be cowardly with respect to men, and audacious with respect to God?

[C’est un vilain vice, que le mentir; & qu’un ancien peint bien honteusement, quand il dit, que c’est donner tesmoignage de mespriser Dieu, & quand & quand de craindre les hommes. Il n’est pas possible d’en representer plus richement l’horreur, la vilité & le desreiglement: Car que peut on imaginer plus vilain, que d’estre couart à l’endroit des hommes, & brave à l’endroit de Dieu?]

Michel de Montaigne (1533-1592) French essayist

Essays, Book 2, ch. 18 (2.18), “Of Giving the Lie [Du Démentir]” (1578–79) [tr. Ives (1925)]
    (Source)

This essay (and passage) appeared in the 1st (1580) edition, and was expanded in each succeeding edition.

The ancient writer mentioned is Plutarch in his Life of Lysander.

(Source (French)). Alternate translations:

To ly is a horrible-filthy vice; and which an auncient writer setteth forth very shamefully, when he saith, that whosoever lieth, witnesseth that he contemneth God and therewithal feareth men. It is impossible more richly to represent the horrour, the vilenesse and the disorder of it: For, What can be imagined so vile, and base, as to be a coward towardes men, and a boaster towardes God?
[tr. Florio (1603)]

Lying is a base vice; a vice that one of the ancients paints in the most odious colours when he says, "That it is too manifest a contempt of God, and a fear of man." It is not possible more copiously to represent the horror, baseness, and irregularity of it; for what can be imagined more vile, than a man, who is a coward towards man, so courageous as to defy his Maker?
[tr. Cotton (1686)]

Lying is a base vice; a vice that one of the ancients portrays in the most odious colors when he says, “that it is to manifest a contempt of God, and withal a fear of men.” It is not possible more fully to represent the horror, baseness, and irregularity of it; for what can a man imagine more hateful and contemptible than to be a coward toward men, and valiant against his Maker?
[tr. Cotton/Hazlitt (1877)]

Lying is a base vice, and painted in its most shameful colours by one of the ancients, who says that to lie is to give proof that you despise god and at the same time are afraid of men. It is impossible to state its horror, its vileness, and its outrageousness more felicitously. For what baser thing can we imagine than to be a coward toward men and act the brave fellow toward God?
[tr. Zeitlin (1934)]

Lying is an ugly vice, which an ancient paints in most shameful colors when he says that it is giving evidence of contempt for God, and at the same time of fear of men. It is not possible to represent more vividly the horror, the vileness, and the profligacy of it. For what can you imagine uglier than being a coward toward men and bold toward God?
[tr. Frame (1943)]

Lying is a villein's vice, a vice which an Ancient paints full shamefully when he says that it gives testimony to contempt for God together with fear of men. It is not possible to show more richly the horror of it, its vileness and its disorderliness. For what can one imagine more serf-like than to be cowardly before men and defiant towards God?
[tr. Screech (1987)]