Dying from the plague, from a stomach ailment, from drowning, or in childbirth is martyrdom.The narrator said, Abu Uthman related this to us many times, and once he traced it back to the Prophet ﷺ.
أخبرنا عبيد الله بن سعيد قال حدثنا يحيى عن التيمي عن أبي عثمان عن عامر بن مالك
الطاعون والمبطون والغريق والنفساء شهادة قال وحدثنا أبو عثمان مرارا ورفعه مرة إلى النبي ﷺ
Sourcing, [sahih] Ahmad narrated it, 6/465, from Yahya bin Saeed Qattan, through the same chain, and it is in Kubra, hadith no. 2181. The hadith has corroborating narrations from Nasai, forthcoming, hadith no. 3165, Bukhari, hadith no. 653, and Muslim, hadith no. 1914/164, and others.Taymi is Sulayman bin Tarkhan, and Abu Uthman is Nahdi, Abdul-Rahman bin Mill.