What did the Prophet Muhammad (saw) reply when 'Umar bin Al-Khattab asked whether one can sleep while they are Junub if they perform ablution?
 Narrated `Umar bin Al-Khattab:                     I asked Allah's Apostle "Can any one of us sleep while he is Junub?" He replied, "Yes, if he performs ablution, he can sleep while he is Junub."