Theophylact of Ohrid

So let not the death of Christ trouble you: for if He had not died, He would not have established the covenant, so that we might be heirs. For it is beyond doubt that a covenant takes effect after death, and we would have been entirely unworthy of the inheritance, since the enmity would not have been destroyed. Read and understand this in the form of a question.

Commentary on Hebrews ↗

Oecumenius

"for it does not take effect while the one who made it lives." Read according to the question.

The Pseudo-Oecumenian Catena on Hebrews ↗