Exodus 39:21-23

Young's Literal Translation

²¹ and they bind the breastplate by its rings unto the rings of the ephod, with a ribbon of blue, to be above the girdle of the ephod, and the breastplate is not loosed from off the ephod, as Jehovah hath commanded Moses.

²² And he maketh the upper robe of the ephod, work of a weaver, completely of blue;

²³ and the opening of the upper robe [is] in its midst, as the opening of a habergeon, a border [is] to its opening round about, it is not rent;