Exodus 28:4

28:4 Now these are the garments that they are to make: a breastpiece, an ephod, a robe, a fitted tunic, a turban, and a sash. They are to make holy garments for your brother Aaron and for his sons, that they may minister as my priests.

Exodus 28:28

28:28 They are to tie the breastpiece by its rings to the rings of the ephod by blue cord, so that it may be above the waistband of the ephod, and so that the breastpiece will not be loose from the ephod.