Umar bin Khattab disagreed with me concerning a woman whose husband had died while she was pregnant. I said, "She may marry once she gives birth."Umm Tufayl, the mother of Umar's child, said in support of me, "The Messenger of Allah ﷺ commanded Sabia al-Aslamiyya to marry once she gave birth."
حدثنا إسحاق بن عيسى قال أخبرني ابن لهيعة عن بكير عن بسر بن سعيد
نازعني عمر بن الخطاب في المتوفى عنها زوجها وهي حامل فقلت تزوج إذا وضعت فقالت أم الطفيل أم ولدي لعمر ولي قد أمر رسول الله ﷺ سبيعة الأسلمية أن تنكح إذا وضعت
Its isnad is hasan, due to Ibn Lahia, while the rest of the narrators are well-known leading scholars. The hadith has already appeared with similar wording at 26594 and its cross-references.