Is it obligatory to wash the hands upon waking up, and how many times? Does this include sleep at night and any [other] sleep? Is it obligatory or recommended? And does whatever the hand touches before washing become impure?

The hadith (When one of you wakes from his sleep, he should not dip his hand into the vessel until he has washed it three times, for he does not know where his hand spent the night) is authentic. It is permissible to wash the hands two or three times upon waking from sleep at night. This ruling is general for both night and day sleep according to the majority of scholars, while Ahmad and Dawud restricted it to night sleep. Washing the hands three times after waking from night sleep is recommended, not obligatory, according to the majority of scholars. Therefore, whoever deviates from this does not commit a sin, nor is the water or the touched item judged impure.