it is recommended, so that her freedom from pregnancy may be known, which is more cautious for the purchaser and more decisive in ending dispute. Ahmad said: If it belongs to a woman, I prefer that she does not sell it until she performs her istibra' with one menstrual cycle, as that is more cautious for her. If he has intercourse with her and she is in menopause, he is not required to perform her istibra' because the absence of pregnancy is known. If she is of the age where she can conceive, he is obligated to perform her istibra'. This is the position of al-Nakha'i and al-Thawri. There is another narration from Ahmad that he is not obligated to perform her istibra', which is the opinion of Abu Hanifah, Malik, and al-Shafi'i, because Abd al-Rahman ibn Awf sold a slave girl he had intercourse with before performing her istibra'. Also, because the obligation of istibra' lies with the purchaser, it is not incumbent upon the seller. The istibra' is more emphasized in the case of a free woman, yet it is not obligatory before or after marriage; likewise, it is not obligatory in the case of a slave girl before or after the sale. Our argument is that Umar criticized Abd al-Rahman ibn Awf for selling a slave girl with whom he had had intercourse [before performing her istibra'. Abdullah ibn Ubayd ibn Umayr reported that Abd al-Rahman ibn Awf sold a slave girl he used to have intercourse with] before performing her istibra', and a pregnancy became apparent to the person who bought her. They took the dispute to Umar, and Umar said to him: "Did you have intercourse with her?" He said: "Yes." He said: "And you sold her before performing her istibra'?" He said: "Yes." He said: "You were not fit to do that." Then he summoned the qafah (experts in physiognomy/lineage), and they examined him and attributed the child to him. Also, because the purchaser is obligated to perform istibra' to preserve his sperm, the seller is likewise obligated. Furthermore, before istibra', the validity and permissibility of the sale are in doubt due to the possibility that she might be an umm walad (mother of a child), so istibra' is mandatory to remove this possibility. If he violates this and sells her, the sale is valid in outward appearance because the fundamental principle is the absence of pregnancy, and because Umar and Abd al-Rahman did not rule that the sale of the slave girl whom he sold before her istibra' was corrupt, except with regard to the attribution of the child to him; had the sale been void before that, such a ruling would not have been necessary. Our companions mentioned two narrations regarding every