We did not know that the Messenger of Allah ﷺ had been buried until we heard the sound of the spades late in the night, on the night of Wednesday. Muhammad said, "The masahi are shovels."
حدثنا عبدة بن سليمان قال حدثنا محمد بن إسحاق عن فاطمة بنت محمد عن عمرة
ما علمنا بدفن رسول الله ﷺ حتى سمعت صوت المساحي من آخر الليل ليلة الأربعاء قال محمد والمساحي المرور
Its isnad is sahih. "Fatimah bint Muhammad" is an old copying error, and she is actually Fatimah bint Munzir, as correctly given in 25927. She is the wife of Hisham bin Urwa, and she is trustworthy, her hadith being accepted by the community of scholars. The hadith was narrated by Bayhaqi 2/49, and it appears in Ibn Majah 1/521 as part of a long hadith numbered 1628, and in Darimi in the introduction 1/40.