2. When the sale is a credit sale, it is compulsory upon both parties to mutually agree upon the date of payment e.g. 30 days from the day of the sale. If the date of payment is left unclear (e.g. when the Haajis return from Hajj) or unfixed (e.g. when I am able, I will pay you), this will not be permissible and will render the sale a faasid (corrupt) sale. The reason for this type of sale being impermissible is that generally this loose arrangement leads to quarrels and disputes.