A single lie destroys a whole reputation for integrity.

[Piérdese con sola una mentira todo el crédito de la entereza.]

Baltasar Gracián y Morales (1601-1658) Spanish Jesuit priest, writer, philosopher

The Art of Worldly Wisdom [Oráculo Manual y Arte de Prudencia], § 181 (1647) [tr. Jacobs (1892)]
    (Source)

(Source (Spanish)). Alternate translations:

By one single lie, a man loses all his good name.
[Flesher ed. (1685)]

A whole reputation for uprightness may be ruined with a single lie.
[tr. Fischer (1937)]

A single lie can destroy your reputation for honesty.
[tr. Maurer (1992)]