Exodus 28:31
And thou shalt make the robe of the ephod all of blue.
Exodus 28:4
And these are the garments which they shall make: the pectoral, the ephod, the robe, the broidered coat, the mitre, and the girdle. Therefore let them make the holy garments for Aaron, thy brother, and his sons, that they may be my priests.
Exodus 28:28
And they shall bind the pectoral by its rings unto the rings of the ephod with a lace of blue, that it may be above the special girdle of the ephod and that the pectoral not be loosed from the ephod.
Exodus 39:22-26
And he made the robe of the ephod of woven work, all of blue,
Leviticus 8:7
And he put upon him the coat and girded him with the girdle and then clothed him with the robe and put the ephod upon him, and he girded him with the special girdle of the ephod and bound it unto him therewith.