I heard the Messenger of Allah (May Peace be upon him) say: When any of you wakes up from sleep, he should not put his hand in the utensil until he washes it three times, for none of you knows where his hand remained during the night or where it went round. (Using translation from Abū Dāʾūd 105)
"إِذَا استيقظ أحدُكم من نومِه فلا يُدخلْ يدَه في الإناءِ حتَّى يغسلَها ثلاثًا، فإنَّ أحدَكم لا يدْرى أينَ باتت يده" .