Translation of the verse 1 from Surah Al-Muzzammil : Number of verses 20 - - page 574 - Part 29.
O you wrapped in garments (i.e. Prophet Muhammad SAW)!
O you who wraps himself [in clothing],
(73:1) O you the (sleeping) enwrapped one! *1
*1) To address the Holy Prophet (upon whom be peace) with these words and then to command him to rise and keep standing in the Prayer at night, shows that at the tune he either lay asleep, or had wrapped himself up in a sheet in order to go to sleep. Here, to address him with "O you who sleeps covered up" instead of with "O Prophet, or O Messenger", is a fine way of address, which by itself gives the meaning: "Gone is the time when you used to enjoy peaceful sleep at will; now you lie under the burden of a great mission, whose demands and duties are different as well as onerous.
Source : Al-Muzzammil Verse 1: O you who wraps himself [in clothing],