Qur'an, An-Nisa, Surah 4:135
Believers, remain resolute in justice and bear witness to the truth, be it against yourselves, your parents, or your kinsfolk. Whether the person concerned is rich or poor, remember that Allah is cognizant of your actions. So do not let your passions take control, lest you swerve from justice. For if you distort the truth or decline to give you testimony, then remember Allah has full knowledge of all that you do.