if you are on a journey and cannot find a writer then a retained pledge . and if one of you entrusts to another let him who is trusted deliver his trust and let him be wary of allah his lord. and do not conceal your testimony anyone who conceals it his heart will indeed be sinful and allah knows well what you do.
وإن كنتم على سفر ولم تجدوا كاتبا فرهان مقبوضة فإن أمن بعضكم بعضا فليؤد الذي اؤتمن أمانته وليتق الله ربه ولا تكتموا الشهادة ومن يكتمها فإنه آثم قلبه والله بما تعملون عليم