Albert Barnes Commentary Hebrews 5:9

"and having been made perfect, he became unto all them that obey him the author of eternal salvation;" — Hebrews 5:9 (ASV)

And being made perfect. That is, being made a complete Savior—a Savior fitted in all respects to redeem people. Sufferings were necessary for the completeness or the finish of His character as a Savior—not to His moral perfection, for He was always without sin. See this explained (see Barnes on Hebrews 2:10).

He became the Author, That is, He was the procuring cause (aitios) of salvation. It is to be traced wholly to His sufferings and death. (See Barnes on Hebrews 2:10).

Unto all them that obey him. It is not to save those who live in sin. Only those who obey Him have any evidence that they will be saved. (See Barnes on John 14:15).