For nothing can ever be virtuous or creditable that is not just.

[Nihil enim honestum esse potest, quod iustitia vacat.]

Marcus Tullius Cicero (106-43 BC) Roman orator, statesman, philosopher

De Officiis [On Duties; On Moral Duty; The Offices], Book 1, ch. 19 (1.19) / sec. 62 (44 BC) [tr. Cockman (1699)]
    (Source)

(Source (Latin)). Alternate translations:

No conduct cannot be honorable which departs from justice.
[tr. McCartney (1798)]

For nothing that is devoid of justice can be a virtue.
[tr. Edmonds (1865)]

Nothing that is devoid of justice can be honorable.
[tr. Peabody (1883)]

There can be no honour without justice.
[tr. Gardiner (1899)]

Right cannot be where justice is not.
[ed. Harbottle (1906)]

Nothing that lacks justice can be morally right.
[tr. Miller (1913)]

Nothing can be morally worthy that lacks justice.
[tr. Edinger (1974)]