Who serve unto the example and shadow of heavenly things, as Moses was admonished of God when he was about to make the tabernacle: for, See, saith he, that thou make all things according to the pattern shewed to thee in the mount. Who serve - Οἱτινες λατρευουσι· Who perform Divine worship.
Unto the example and shadow - Υποδειγματι και σκιᾳ, With the representation and shadow; this is Dr. Macknight's translation, and probably the true one.
The whole Levitical service was a representation and shadow of heavenly things; it appears, therefore, absurd to say that the priests served Unto an example or representation of heavenly things; they served rather unto the substance of those things, With appropriate representations and shadows.
As Moses was admonished - Καθως κεχρηματισται Μωσης· As Moses was Divinely warned or admonished of God.
According to the pattern - Κατα τον τυπον· According to the type, plan, or form. It is very likely that God gave a regular plan and specification of the tabernacle and all its parts to Moses; and that from this Divine plan the whole was constructed. See on Exodus 25:40 (note).