Kim Clement pointed this out and the reason is terrific. Here God is speaking to Moses.
Exodus 33:23 and you shall see My back; but My face shall not be seen.”
By standing behind God, Moses only looks into the future. God does not want us looking at the past. Those who live in the past are depressed and unhappy; they try to make the present either fit the past or correct it. They are often unable to believe new ideas or correct old ones. It is a futilre existence. Can’t be done.
Future-oriented people have hope and hope can generate faith in them and others. The just live by faith and without faith it is impossible to please God. If God isn’t pleased, you won’t be either.
Hebrews 11:6 But without faith it is impossible to please Him, for he who comes to God must believe that He is, and that He is a rewarder of those who diligently seek Him
The quotation “the just live by faith” appears seven times in scripture. And seven is symbolically the number of maturity, therefore words to live by.