Exodus 26:12

Then what will be left over of the canopies which are prepared for the roof, that is, one canopy which is in excess, from half of it you shall cover the back of the tabernacle

Other versions

King James Version

And the remnant that remaineth of the curtains of the tent, the half curtain that remaineth, shall hang over the backside of the tabernacle.

English Standard Version

And the part that remains of the curtains of the tent, the half curtain that remains, shall hang over the back of the tabernacle.

New International Version

As for the additional length of the tent curtains, the half curtain that is left over is to hang down at the rear of the tabernacle.