NET
20 For the bed is too short to stretch out on, and the blanket is too narrow to wrap around oneself.
Darby
20 For the bed is too short to stretch oneself on, and the covering too narrow when he would wrap himself in it.
KJV
20 For the bed is shorter than that [a man] can stretch himself [on it]: and the covering narrower than that he can wrap himself [in it].