Bulugh al-Maram, Book 1, Hadith 43 (English) ⓘ

Narrated Abu Huraira (rad): Allah’s Messenger said: “When one of you wakes up from his sleep, he must not put his hand in a utensil till he washed it three times, for he does not know where his hand was (while he slept)”. [Agreed upon. This is Muslim’s version].

وَعَنْهُ: { إِذَا اِسْتَيْقَظَ أَحَدُكُمْ مِنْ نَوْمِهِ فَلَا يَغْمِسُ يَدَهُ فِي اَلْإِنَاءِ حَتَّى يَغْسِلَهَا ثَلَاثًا فَإِنَّهُ لَا يَدْرِي أَيْنَ بَاتَتْ يَدَهُ } مُتَّفَقٌ عَلَيْهِ.‏ وَهَذَا لَفْظُ مُسْلِم ٍ (49)‏.‏ ‏5 ‏- صحيح.‏ رواه البخاري (162)‏، ومسلم (278)‏.‏