And if you are on a journey and you do not find a writer (for the contract) then a security may be taken into possession, then if one of you entrusts another (with something) then he who is entrusted should deliver that which is entrusted to him and let him fear Allah, his Fosterer; and do not hide the testimony and one who hides it then his heart is certainly sinful; and Allah is the Knower of what you do. (R 39)