The Messenger of Allah ﷺ used to observe spiritual retreat during the last ten days of Ramadan until Allah took him.
حدثنا عبد الرزاق حدثنا معمر عن الزهري عن عروة
أن رسول الله ﷺ كان يعتكف العشر الأواخر من رمضان حتى قبضه الله عز وجل
Its isnad is sahih. It was previously mentioned at 25331.