سورة Al-Maidah ( The Table spread with Food ) - الآية 108

That should make it closer (to the fact) that their testimony would be in its true nature and shape (and thus accepted), or else they would fear that (other) oaths would be admitted after their oaths. And fear Allah and listen (with obedience to Him). And Allah guides not the people who are Al-Fasiqun (the rebellious and disobedient).