This verse now adds a further elucidation. It was enough that the relative worth of the Son and of the angels was described in verse 4, but that left open the question of how they relate to each other.
If angels are to worship the Son, how much more should man do so! Can mortal man overthrow the order of worship in heaven and teach the angels to desist because he refuses to acknowledge his Creator? Man brings a curse on himself by refusing to worship Christ as God.
The text quoted is from Deuteronomy 32:43. These words are not found in the Masoretic text on which the KJV Old Testament is based, but in the older Septuagint reading, and may indicate an original reading lost from the Masoretic text. Regardless, the use of this text by the Epistle to the Hebrews establishes it as inspired by God and to be received as the word of God.