is invalid, and the price becomes immediately due rather than deferred. The reason for this is uncertainty.
However, the correct view is that it is valid, based on textual and rational evidence.
First: the hadith of Aisha (may Allah be pleased with her), who said to the Prophet (peace and blessings be upon him), “So-and-so has brought cloth from Syria. Why do you not send word to him to sell you two garments on credit until financial ease?” So he sent word to him, but he refused. (1) Perhaps he refused because he wished to clear his stock and bring in other goods. There is nothing wrong with refusing to sell when it does not suit one, just as Jabir (may Allah be pleased with him) refused. (2)
As for the rational evidence: so long as the seller knows that the buyer is insolvent, he is not legally entitled to demand payment from him until he becomes financially able. He is obliged to grant him respite, whether this is stipulated or not, because Allah says:
“And if someone is in hardship, then let there be postponement until ease.” [al-Baqarah: 280]
Thus, this condition does no more than affirm the obligation to grant respite, and granting respite is obligatory. For this reason, the correct view in this issue is that it is permissible.
His statement, “and that the slave be able to write”: that is, if a person purchases a slave who has been offered for sale and says, “On condition that he be able to write,” the condition is valid, because it is a quality sought in the item sold.
However, the phrase “able to write” entails some uncertainty, because handwriting