Subayah al-Aslamiyyah gave birth a few nights after her husband's death. The Messenger of Allah ﷺ said to her, "You are now free to remarry, so marry whomever you wish."
حدثنا روح قال ثنا مالك بن أنس عن هشام بن عروة عن أبيه أن المسور بن مخرمة أخبره قال وثنا إسحاق يعني ابن الطباع قال أخبرني مالك عن هشام عن أبيه
أن سبيعة الأسلمية نفست بعد وفاة زوجها بليال فقال لها رسول الله ﷺ قد حللت فانكحي
Its isnad is sahih. Its narrators are well-known and trustworthy, and the hadith has already appeared with similar wording. It is found in Bukhari 7/73, in the chapter on divorce, "and pregnant women, their term is until they deliver their burden," and in Muslim 2/1122, no. 1484, in the chapter on divorce, on the completion of the waiting period of a woman whose husband has died, and in Tirmidhi 3/489, no. 1193, and Nasai 6/190, no. 3506, and Ibn Majah 1/654, no. 2029.