witnesses told to be truthful, 2:283, 5:8, 25:72

And if you are on a journey and cannot find a scribe, then let there be a pledge taken (mortgaging); then if one of you entrust the other, let the one who is entrusted discharge his trust (faithfully), and let him be afraid of Allah, his Lord. And conceal not the evidence for he, who hides it, surely his heart is sinful. And Allah is All-Knower of what you do. (2:283)

O you who believe! Stand out firmly for Allah and be just witnesses and let not the enmity and hatred of others make you avoid justice. Be just: that is nearer to piety, and fear Allah. Verily, Allah is Well­Acquainted with what you do." (5:8)

And those who do not witness falsehood, and if they pass by some evil play or evil talk, they pass by it with dignity." (25:72)