The Messenger of Allah ﷺ said, "When one of you wakes from sleep, let him wash his hand before dipping it into the water for ablution, for none of you knows where his hand spent the night."
أن رسول الله ﷺ قال: إذا استيقظ أحدكم من نومه فليغسل يده قبل أن يدخلها في وضوئه؛ فإن أحدكم لا يدري أين باتت يده.
Malik narrated it in the Book of Purification (9) from Abu Zinad, from Araj, from Abu Hurairah, who said, then he mentioned it.Bukhari narrated it in the Book of Wudu (162) through Malik's route, with the same wording, except that he combined this hadith with the hadith, "When one of you performs wudu, let him put water in his nose and then blow it out, and whoever cleans himself with stones let him use an odd number," perhaps because their chains of transmission were identical. Malik, however, separated the two, and likewise Muslim, for he narrated it in the Book of Purification (278) through the route of Mughira Hizami, from Abu Zinad, from him, with the same wording, and he also narrated it through other routes from Abu Hurairah.