Abu Huraira reported God's messenger as saying, “When one of you awakes from sleep he must not dip his hand in the vessel till he has washed it three times, for he does not know where his hand was during the night.” (Bukhari and Muslim.)
Hadith Referenceمشكوة المصابيح / كتاب الطهارة / 391
Hadith Gradingالألبانی:مُتَّفَقٌ عَلَيْهِ | زبیر علی زئی:متفق عليه
Hadith Takhrij´تحقيق و تخريج: محدث العصر حافظ زبير على زئي رحمه الله` «متفق عليه، رواه البخاري (162) و مسلم (87/ 278)»