It is a confusing phrase:
In “subjecting” all things to him,
he left nothing not “subject to him.”
The book of Hebrews we think was written for priests. How a priest should think. How we are to know God. How we are to love God. Explaining our liturgy. Hebrews is thick with theology. And even though we can say we know and understand much of the book of Hebrews I would dare say we know little of what is contained in the is amazing book of the Bible.
The phrase above for example, all things are subjected to him. The Him is Jesus. As the second person of the Trinity, God has given everything over to Him. Everything has been made subject to Him.
What does Jesus do with all this power and authority? He left nothing subject to Himself. He gave it all away. He emptied Himself of everything. He kept nothing back; He kept nothing for Himself. He poured Himself out for you, for me, for all. He became little less than the angels.
In a sense, we, as disciples, are called to empty ourselves, give everything back to God. Jesus was made perfect through suffering. My dear friends, so are we.
May the Lord bless you in the name of the Father and if the Son and of the Holy Spirit. Amen