Leviticus 8:7 (ESV)

7 And he put the coat on him and tied the sash around his waist and clothed him with the robe and put the ephod on him and tied the skillfully woven band of the ephod around him, binding it to him with the band.

The robe (mᵉîl) was a vestment specifically for the high-priest (Exodus 28:31–34; Exodus 39:22–26). It was made of blue material and was worn over the coat.