People who are too much concerned with little things usually become incapable of big ones.
 
[Ceux qui s’appliquent trop aux petites choses deviennent ordinairement incapables des grandes.]

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

Réflexions ou sentences et maximes morales [Reflections; or Sentences and Moral Maxims], ¶41 (1665-1678) [tr. Kronenberger (1959)]
    (Source)

Present from the 1665 edition. See here for more discussion (English).

(Source (French)). Alternate translations:

They that use to employ their minds too much upon Trifles, commonly make themselves incapable of any thing that is serious or great.
[tr. Stanhope (1694), ¶42]

Those who apply themselves too much to little things, commonly become incapable of great ones.
[pub. Donaldson (1783), ¶38; ed. Lepoittevin-Lacroix (1797), ¶41]]

Those who apply themselves much to little things, commonly become incapable of great ones.
[ed. Carville (1835), ¶35]

Those who bestow too much application on trifling things, become generally incapable of great ones.
[ed. Gowens (1851), ¶42]

Those who apply themselves too closely to little things often become incapable of great things.
[tr. Bund/Friswell (1871)]

Undue attention to details tends to unfit us for greater enterprises.
[tr. Heard (1917)]

Too close attention to trifles generally breeds incapacity in matters of moment.
[tr. Stevens (1939)]

Men too involved in details usually become unable to deal with great matters.
[tr. FitzGibbon (1957)]

People too much taken up with little things usually become incapable of big ones.
[tr. Tancock (1959)]

Those who apply themselves too much to little things, ordinarily become incapable of great ones.
[tr. Whichello (2016)]