Exodus 28:31
"You are to make the robe of the ephod entirely of blue.
Exodus 28:4
These are the garments that they are to make: a breast piece, an ephod, a robe, a checkered tunic, a turban, and a sash. They are to make holy garments for Aaron your brother and for his sons to serve me as priests.
Exodus 28:28
They are to fasten the rings on the breast piece to the rings on the ephod with a blue cord so it will rest on the skillfully woven band of the ephod and so the breast piece won't come loose from the ephod.
Exodus 39:22-26
He made the robe of the ephod of woven work, entirely of blue.
Leviticus 8:7
Then he clothed Aaron with the tunic, girded him with the band for priests, clothed him with the robe, placed the ephod on him, girded him with the skillfully woven band of the ephod, and bound it on him.