We did not know where the Messenger of Allah ﷺ would be buried until we heard the sound of the spades during the last part of the night, on the eve of Wednesday.Ibn Ishaq said, "The masahi are the iron shovels."
حدثنا عبدة قال حدثنا محمد بن إسحاق عن فاطمة بنت محمد عن عمرة
ما علمنا أين يدفن رسول الله ﷺ حتى سمعنا صوت المساحي من آخر الليل ليلة الأربعاء قال ابن إسحاق والمساحي المرور
Its isnad is sahih. It previously appeared at 24214. Fatimah bint Munzir is trustworthy, and her hadith is recorded by all the compilers of the six major collections. Her name appears in the copy of Atraf Musnad 9/357, number 12407, as Fatimah bint Muhammad, but this is a scribal error. See also the references for her biography.