We make promises to the extent that we hope, and keep them to the extent that we fear.

[Nous promettons selon nos espérances, et nous tenons selon nos craintes.]

François VI, duc de La Rochefoucauld (1613-1680) French epigrammatist, memoirist, noble

Réflexions ou sentences et maximes morales [Reflections; or Sentences and Moral Maxims], ¶38 (1665-1678) [tr. Kronenberger (1959)]
    (Source)

Present from the 1st edition in 1665.

(Source (French)). Alternate translations:

Our Promises are always made with a reflection on our Hopes, and perform'd according to our fears.
[tr. Davies (1669), ¶16]

We promise in proportion to our Hopes,
and we keep in proportion to our Fears
[tr. Stanhope (1694), ¶39]

We promise in proportion to our Hopes, and we keep our Word in proportion to our Fears.
[tr. Stanhope (1706), ¶39]

We promise according to our hopes, and perform according to our fears.
[pub. Donaldson (1783), ¶357; [ed. Lepoittevin-Lacroix (1797); ed. Gowens (1851), ¶39]

We promise according to our hopes; we perform according to our fears.
[ed. Carville (1835), ¶463; tr. Bund/Friswell (1871)]

Promises are measured by hope; performances by fear.
[tr. Heard (1917)]

Our promises are measured by our hopes; our performances by our fears.
[tr. Stevens (1939)]

Our promises are made in hope, and kept in fear.
[tr. FitzGibbon (1957)]

Our promises are made in proportion to our hopes, but kept in proportion to our fears.
[tr. Tancock (1959)]

We make promises according to our hopes, and keep them according to our fears.
[tr. Whichello (2016)]