Speak out on behalf of the voiceless,
and for the rights of all who are vulnerable.
Speak out in order to judge with righteousness
and to defend the needy and the poor.

The Bible (The Old Testament) (14th - 2nd C BC) Judeo-Christian sacred scripture [Tanakh, Hebrew Bible], incl. the Apocrypha (Deuterocanonicals)

Proverbs 31:8-9 [CEB (2011)]
    (Source)

From the sayings of King Lemuel of Massa, given by his mother. Alternate translations:

Open thy mouth for the dumb in the cause of all such as are appointed to destruction. Open thy mouth, judge righteously, and plead the cause of the poor and needy.
[KJV (1611)]

Speak, yourself, on behalf of the dumb, on behalf of all the unwanted; speak, yourself, pronounce a just verdict, uphold the rights of the poor, of the needy.
[JB (1966)]

Speak up for people who cannot speak for themselves. Protect the rights of all who are helpless. Speak for them and be a righteous judge. Protect the rights of the poor and needy.
[GNT (1976)]

Make your views heard, on behalf of the dumb, on behalf of all the unwanted; make your views heard, pronounce an upright verdict, defend the cause of the poor and the wretched.
[NJB (1985)]

Speak out for those who cannot speak,
for the rights of all the destitute.
Speak out; judge righteously;
defend the rights of the poor and needy.
[NRSV (2021 ed.)]

Speak up for the dumb,
For the rights of all the unfortunate.
Speak up, judge righteously,
Champion the poor and the needy.
[RJPS (2023 ed.)]