329 The first part of the verse deals with transactions involving future payment or future consideration, and the second part with transactions in which payment and delivery are made on the spot. Examples of the former are if goods are brought now and payment is promised at a fixed time and place in the future, or if cash is paid now and delivery is contracted for at a fixed time and place in the future. In such cases a written document is recommended, but it is held that the words later on in this verse, that it is 'juster... more suitable as evidence, and more convenient to prevent doubts," etc., imply that it is not obligatory in law. Examples of the latter kind-cash payment and delivery on the spot-require no evidence in writing, but apparently oral witnesses to such transactions are recommended. 330 The scribe in such matters assumes a fiduciary capacity; he should therefore remember to act as in the presence of Allah, with full justice to both parties. The art of writing he should look upon as a gift from Allah, and he should use it as in His service. In an illiterate population the scribe's position is still more responsible. 331 Possibly the person "mentally deficient, or weak, or unable to dictate," may also be incapable of making a valid contract, and the whole duty would be on his guardian, who again must act in perfect good faith, not only protecting but vigilantly promoting the interests of his ward. 332 It is desirable that the men (or women) who are chosen as witness should be from the circle to which the parties belong, as they would best be able to understand the transaction, and be most easily available if their evidence is required in future. 333 Commercial morality is here taught on the highest plane and yet in the most practical manner, both as regards the bargains to be made, the evidence to be provided, the doubts to be avoided, and the duties and rights of scribes and witnesses. Probity even in worldly matters is to be, not a mere matter of convenience or policy, but a matter of conscience and religious duty. Even our everyday transactions are to be carried out as in the presence of Allah. 334 A pledge or security stands on its own independent footing, though it is a very convenient form of closing the bargain where the parties cannot trust each other, and cannot get a written agreement with proper witnesses. 335 The Law of Deposit implies great trust in the Depositary on the part of the Depositor. The Depositary becomes a trustee, and the doctrine of Trust can be further developed on that basis. The trustee's duty is to guard the interests of the person on whose behalf he holds the trust and to render back the property and accounts when required according to the terms of the trust. This duty again is linked to the sanction of Religion, which requires a higher standard than Law. 336 It sometimes happens that if some inconvenient piece of evidence is destroyed or concealed, we gain a great advantage materially. We are warned not to yield to such a temptation. The concealment of evidence has a serious effect on our own moral and spiritual life, for it taints the very source of higher life, as typified by the heart. The heart is also the seat of our secrets. We are told that the sin will reach our most secret being, though the sin may not be visible or open to the world. Further, the heart is the seat of our affections, and false dealing taints all our affections.