Al-Baqara 2:282

O you who believe, when you contract a debt among yourselves for a fixed period of time, write it down, and let the scribe write it between you with fairness. The scribe whom Allah has taught should not refuse to write, so let him write, and let the debtor dictate, but he should fear Allah his Lord, and not diminish anything out of it. If the debtor is feeble-minded, weak, or unable to dictate, then let his guardian dictate fairly, and bring two witnesses from among your men; if two men are not available, then one man and two women from those whom you accept as witnesses – so that if one of them forgets, the other can remind her. The witnesses should not refuse when they are summoned. Do not be reluctant to write down your debts, whether the amount is small or large, for a fixed period of time; that is more equitable in the sight of Allah, and more supportive as evidence, and more likely to prevent doubts among yourselves. However, if you are conducting a transaction on the spot between yourselves, there is no blame upon you not to write it, but take witnesses whenever you trade with one another. Neither a scribe nor a witness should suffer harm, for if you do cause them harm, it is indeed a sin on your part. So fear Allah, for it is Allah Who teaches you, and Allah is All-Knowing of everything[172].

[172] This is known as Āyat ad-Dayn, the verse of debt, and it is the longest verse in the Qur’an.

O you who have believed, when you contract a debt for a specified term, write it down. And let a scribe write [it] between you in justice. Let no scribe refuse to write as Allāh has taught him. So let him write and let the one who has the obligation [i.e., the debtor] dictate. And let him fear Allāh, his Lord, and not leave anything out of it. But if the one who has the obligation is of limited understanding or weak or unable to dictate himself, then let his guardian dictate in justice. And bring to witness two witnesses from among your men. And if there are not two men [available], then a man and two women from those whom you accept as witnesses - so that if one of them [i.e., the women] errs, then the other can remind her. And let not the witnesses refuse when they are called upon. And do not be [too] weary to write it, whether it is small or large, for its [specified] term. That is more just in the sight of Allāh and stronger as evidence and more likely to prevent doubt between you, except when it is an immediate transaction which you conduct among yourselves. For [then] there is no blame upon you if you do not write it. And take witnesses when you conclude a contract. Let no scribe be harmed or any witness. For if you do so, indeed, it is [grave] disobedience in you. And fear Allāh. And Allāh teaches you. And Allāh is Knowing of all things.

282. O you who believe! When you contract a debt for a fixed period, write it down. Let a scribe write it down in justice between you. Let not the scribe refuse to write as Allâh has taught him, so let him write. Let him (the debtor) who incurs the liability dictate, and he must fear Allâh, his Lord, and diminish not anything of what he owes. But if the debtor is of poor understanding, or weak, or is unable to dictate for himself, then let his guardian dictate in justice. And get two witnesses out of your own men. And if there are not two men (available), then a man and two women, such as you agree for witnesses, so that if one of them (two women) errs, the other can remind her. And the witnesses should not refuse when they are called (for evidence). You should not become weary to write it (your contract), whether it be small or big, for its fixed term, that is more just with Allâh; more solid as evidence, and more convenient to prevent doubts among yourselves, save when it is a present trade which you carry out on the spot among yourselves, then there is no sin on you if you do not write it down. But take witnesses whenever you make a commercial contract. Let neither scribe nor witness suffer any harm, but if you do (such harm), it would be wickedness in you. So be afraid of Allâh; and Allâh teaches you. And Allâh is the All-Knower of each and everything.

O ye who believe! When ye contract a debt for a fixed term, record it in writing. Let a scribe record it in writing between you in (terms of) equity. No scribe should refuse to write as Allah hath taught him, so let him write, and let him who incurreth the debt dictate, and let him observe his duty to Allah his Lord, and diminish naught thereof. But if he who oweth the debt is of low understanding, or weak, or unable himself to dictate, then let the guardian of his interests dictate in (terms of) equity. And call to witness, from among your men, two witnesses. And if two men be not (at hand) then a man and two women, of such as ye approve as witnesses, so that if the one erreth (through forgetfulness) the other will remember. And the witnesses must not refuse when they are summoned. Be not averse to writing down (the contract) whether it be small or great, with (record of) the term thereof. That is more equitable in the sight of Allah and more sure for testimony, and the best way of avoiding doubt between you; save only in the case when it is actual merchandise which ye transfer among yourselves from hand to hand. In that case it is no sin for you if ye write it not. And have witnesses when ye sell one to another, and let no harm be done to scribe or witness. If ye do (harm to them) lo! it is a sin in you. Observe your duty to Allah. Allah is teaching you. And Allah is knower of all things.