Quran 5:108 — The Feast (Al-Ma'edah)

This is more apt to encourage an honest testimony on their part, fearing that their oath may be disregarded like that of the previous witnesses. You shall observe GOD and listen. GOD does not guide the wicked.

[5:107] If the witnesses are found to be guilty of bias, then two others shall be asked to take their places. Choose two persons who were victimized by the first witnesses, and let them swear by GOD: "Our testimony is more truthful than theirs; we will not be biased. Otherwise, we will be transgressors."

[5:109] The day will come when GOD will summon the messengers and ask them, "How was the response to you?" They will say, "We have no knowledge. You are the Knower of all secrets."