The Messenger of Allah ﷺ said, "When one of you wakes up, he should not dip his hand into the water for washing until he has washed it, for he does not know where his hand spent the night."
حدثنا يزيد حدثنا محمد يعني ابن إسحاق عن موسى بن يسار
قال رسول الله ﷺ إذا استيقظ أحدكم فلا يضعن يده في الغسل حتى يغسلها فإنه لا يدري أين باتت يده