Is washing the hands three times before starting Wudu obligatory, especially upon waking from night sleep?
Chapter on Siwak and the Sunnah of Wudu
Al-Mughni
Book of Purification
Primary text
Washing the hands at the beginning of Wudu is generally recommended whether one has woken up from sleep or not, as the hands are immersed in the water container. However, there is a difference of opinion regarding its obligation upon waking from night sleep. The strong position is that it is obligatory upon waking from night sleep, based on the Prophet's command: 'When one of you wakes from sleep, let him wash his hands three times before putting them into the container, for he does not know where his hand spent the night.' This command implies obligation. This ruling is specifically tied to the night sleep because the phrase 'where his hand spent the night' implies the night, making it inappropriate to strictly analogize it to daytime sleep.
Supporting text
The view that washing the hands is only recommended (Sunnah) and not obligatory is held by 'Ata, Malik, Awza'i, Shafi'i, Ishaq, Ahl al-Ra'y, and Ibn al-Mundhir. They base this on the generality of the verse {When you rise to perform prayer, wash your faces...} (Quran 5:6) and the fact that the command is explained by a reason (not knowing where the hand was) which suggests admonishment (recommendation) rather than strict obligation, as doubt concerning purity does not invalidate established purity.