Exodus 26:13

The foot and a half ¹  on the one side and the foot and a half on the other side of what remains in the length of the curtains of the tent will hang over the sides of the tabernacle, on one side and the other side, to cover it. ² 

Ex 26:2,8

¹ tn Literally “cubit.”

² sn U. Cassuto states the following: “To the north and to the south, since the tent curtains were thirty cubits long, there were ten cubits left over on each side; these covered the nine cubits of the curtains of the tabernacle and also the bottom cubit of the boards, which the tabernacle curtains did not suffice to cover. It is to this that v. 13 refers” (Exodus, 353).