Surah An-Nisa, Verse 135:
يَا أَيُّهَا الَّذِينَ آمَنُوا كُونُوا قَوَّامِينَ بِالْقِسْطِ شُهَدَاءَ لِلَّهِ وَلَوْ عَلَىٰ أَنفُسِكُمْ أَوِ الْوَالِدَيْنِ وَالْأَقْرَبِينَ إِن يَكُنْ غَنِيًّا أَوْ فَقِيرًا فَاللَّهُ أَوْلَىٰ بِهِمَا فَلَا تَتَّبِعُوا الْهَوَىٰ أَن تَعْدِلُوا وَإِن تَلْوُوا أَوْ تُعْرِضُوا فَإِنَّ اللَّهَ كَانَ بِمَا تَعْمَلُونَ خَبِيرًا

O you who believe! Stand out firmly for justice, as witnesses to Allah, even though it be against yourselves, or your parents, or your kin, be he rich or poor, Allah is a Better Protector to both (than you). So follow not the lusts (of your hearts), lest you may avoid justice, and if you distort your witness or refuse to give it, verily, Allah is Ever Well-Acquainted with what you do.

(English – Mohsin Khan)