en_tn_condensed/deu/13/03.md

of which he spoke to you and said, 'Let us go after other gods, that you have not known, and let us worship them,' do not

This can be translated as an indirect quotation. Alternate translation: "and he tells you to serve and worship other gods which you have not known, do not" (See: rc://en/ta/man/translate/figs-quotations)

do not listen to the words of that prophet, or to that dreamer of dreams

"do not listen to what that prophet say nor to what the dreamer of dreams says"

with all your heart and with all your soul

Here "heart" and "soul" are metonyms for a person's inner being. These two phrases are used together to mean "completely" or "earnestly." See how you translated this in Deuteronomy 4:29. (See: rc://en/ta/man/translate/figs-metonymy and rc://en/ta/man/translate/figs-doublet)