The blood of the sacrifices is a proof of a soul making its offerings to God; and it is not in accordance with the divine law that things which will not unite should be mingled together.

From the same author, on #Ex 23:20.

One must suppose that the angel mentioned a little before indicated the voice of God; for the prophet is the messenger of the Lord, who is the real speaker; for it is inevitable that he who hears with his ears, that is to say who firmly receives what is said, must also accomplish what is said to him by his actions; for an action is the proof of what is said; and he who is obedient to what is said, and who performs actions corresponding to his orders, must of necessity have him who has commanded him for his ally and champion, who in appearance indeed brings assistance to his pupil, but in reality to his own doctrines and commandments, … which his enemies and adversaries seek to overthrow.