The quotation in verse 40 is from the writings of Moses.
“This is the man Moses who was among the Israelites”
The phrase “This is the man” throughout this passage refers to Moses.
God was the one who gave those words. AT: “this is the man to whom God spoke living words to give to us”
Possible meanings are 1) “a message that endures” or 2) “words that give life.” (See: rc://en/ta/man/translate/figs-metonymy)
This metaphor emphasizes their rejection of Moses. AT: “they rejected him as their leader” (See: rc://en/ta/man/translate/figs-metaphor)
To do something in the heart is a metonym for desiring to to something. AT: “they desired to turn back” (See: rc://en/ta/man/translate/figs-metonymy)
“When they decided to return to Egypt”