Exodus 28:31

28:31 “You are to make the robe of the ephod completely blue.

Exodus 28:37

28:37 You are to attach to it a blue cord so that it will be on the turban; it is to be on the front of the turban,

Exodus 39:30-31

39:30 They made a plate, the holy diadem, of pure gold and wrote on it an inscription, as on the engravings of a seal, “Holiness to the Lord.” 39:31 They attached to it a blue cord, to attach it to the turban above, just as the Lord had commanded Moses.

Numbers 15:38

15:38 “Speak to the Israelites and tell them to make tassels for themselves on the corners of their garments throughout their generations, and put a blue thread on the tassel of the corners.