This is direct quotation. It can also be stated as an indirect quotation: “God said he would give Abram a son from his own body, and would give the land of Canaan to his descendants.” (See: [[rc://en/ta/man/translate/figs-quotations]])
With his own body Abram would cause his wife to become pregnant, so that together they would have their own, natural son. This was an amazing promise, since Abram and Sarai were very old.