Explanation

Sa‘d ibn Khawlah (may Allah be pleased with him) died leaving behind his wife Subay‘ah al-Aslamiyyah who was pregnant at the time. Soon after his death she gave birth. Once she became pure from her post-natal bleeding, and knowing that her ‘Iddah was over with the childbirth and that it was permissible for her to marry, she adorned and beautified herself. Abu As-Sanābil entered upon her as she was thus beautified and adorned, and realized that she had done so in order to appeal to the suitors. So, he swore by Allah, based upon his knowledge at that time, that it was not permissible for her to marry unless four months and ten days had passed after the death of her husband, based upon Allah's statement in the Qur'an: {And those who are taken in death among you and leave wives behind - they (the wives, shall) wait four months and ten (days)} [Sūrat al-Baqarah : 234]. As Subay‘ah was uncertain about the knowledge she had of this issue, and Abu As-Sanābil affirmed his claim by swearing by Allah, she went to the Prophet (may Allah's peace and blessings be upon him) and asked him about it. The Prophet (may Allah's peace and blessings be upon him) gave her a religious verdict stating that it was permissible for her to marry as soon as she gave birth. If she wished to marry, then she was entitled to it, based on Allah's words in the Qur'an: {And for those who are pregnant, their term is until they give birth} [Sūrat At-Talāq: 4]. Hence, the woman whose husband died while she is pregnant, her waiting period ends when she delivers her child, and the woman who is not pregnant, her waiting period is four months and ten days.