I have a book called 'The Holiest of All' by Andrew Murray, which speaks the truth to me about the teaching of the Epistle to the Hebrews.
Here is an excerpt:
'Our Lord Jesus learned obedience by the things which He suffered. Through this obedience He was made perfect, and became the cause of eternal salvation to all that obey Him. So he entered heaven as our High priest, a Son, perfected for evermore.
The word perfect is one of the keywords of the Epistle. It occurs thirteen times. Four times in regard to the Old Testament, which could make nothing perfect (vii.19). Sacrifices that cannot, as touching the conscience, make the worshipper perfect (ix.9). The law can never make perfect them that draw nigh (x.1). That apart from us they should not be made perfect (xi.40). As great as is the difference between a promise and its fulfilment, or hope and the thing hoped for, between the shadow and substance, is the difference between the Old and New Testament. The law made nothing perfect: it was only meant to point to something better, to the perfection Jesus Christ was to bring.'
I believe we have to be careful not to slip back into a form of legalism, brought about by a misunderstanding of what Christ came to bring.