Sayyiduna Abu Hurairah (may Allah be pleased with him) narrates: The Prophet Muhammad (peace and blessings be upon him) said: "When any one of you wakes up from sleep, he should not dip his hand into a vessel until he has washed it three times, for he does not know where his hand was (on his body) during the night."
Hadith Referenceصحیح ابن حبان / كتاب الطهارة / 1065
Hadith Gradingفضيلة الشيخ الإمام محمد ناصر الدين الألبانيصحيح: م - انظر ما قبله.فضيلة الشيخ العلّامة شُعيب الأرناؤوطإسناده صحيح على شرط مسلم.