Ya ayyuha almuzzammil (surah Muzammil: 1)

Tafseer Tafheem-ul-Quran by Syed Abu-al-A'la Maududi

(73:1) O you the (sleeping) enwrapped one! *1

Yaw ayyuhal muzzammil

*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.