20. Ibn Mahbub has narrated from Hisham ibn Salim from abu Basir who has said the following: “I once asked abu Ja‘far عليه السلام, about the case of a man who marries a woman and who says that she is pregnant and that she is his sister because of breastfeeding and that she has not completed her waiting period. He (the Imam) said, ’If he has gone to bed (engaged in sexual intercourse) with her, he must not accept her words but if he has not done so, he must investigate if he did not know before.’”