We launched a military campaign in the land of the Romans, and the commander of that army was Fadala bin Ubayd al-Ansari. He mentioned the hadith and then Fadala said, "Make them level, for I heard the Messenger of Allah ﷺ command that graves be made level."
حدثنا يعقوب حدثنا أبي عن ابن إسحاق عن يزيد قال حدثني
غزونا أرض الروم وعلى ذلك الجيش فضالة بن عبيد الأنصاري فذكر الحديث فقال فضالة خففوا فإني سمعت رسول الله ﷺ يأمر بتسوية القبور
No references are available.
Its isnad is sahih, mentioned previously at 23818.