Surah An-Nisa' (The Women), Verse 105

اِنَّاۤ اَنْزَلْنَاۤ اِلَیْكَ الْكِتٰبَ بِالْحَقِّ لِتَحْكُمَ بَیْنَ النَّاسِ بِمَاۤ اَرٰىكَ اللّٰهُ وَلَا تَكُنْ لِّلْخَآىِٕنِیْنَ خَصِیْمًا ۟

Innaaa anzalnaaa ilaikal Kitaaba bilhaqqi litahkuma bainan naasi bimaaa araakal laah; wa laa takul lilkhaaa'ineena khaseemaa

“We have sent down to thee the Book in truth, that thou mightest judge between men, as guided by Allah: so be not (used) as an advocate by those who betray their trust;”

Quran 4:105 (Yusuf Ali Translation)