The Messenger of Allah ﷺ said, "You are counted as martyrs through being killed, through the plague, through drowning, through abdominal illness, and a woman who dies in childbirth with her child still within her."
قال رسول الله ﷺ: تستشهدون بالقتل، والطاعون، والغرق، والبطن، وموت المرأة جمعا موتها في نفاسها.
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Abu Bakr bin Abu Shayba narrated it in his Musnad (1920 - Matalib), and from him Abd bin Humayd (154), and by his route Diya in al-Mukhtara (2/225), and Bazzar (1191), all of them narrating the hadith from Abu Bakr bin Hafs bin Umar bin Saad, from Umar bin Saad, from his father Saad bin Abu Waqqas, who related it. Bazzar said, "We do not know of this hadith being narrated from Saad except through this route with this chain of transmission." Its chain is sahih.Busiri likewise judged it sahih in Ithaf Khayra (3/184), saying, "Abu Bakr bin Abu Shayba narrated it, and from him Abd bin Humayd, with a sahih chain."Haythami said in Majma (5/301), "Bazzar narrated it, and its narrators are the narrators of the sahih." However, Daraqutni holds that the mursal version is more likely to be correct. See Ilal of Daraqutni (622).Note, several corruptions occur in Matalib Aliyah, so be aware of this.