certainly return. Figure of speech Polyptoton (returning. will return) for emphasis.
lo! Figure of speech Asterismos. App-6. heard. Hebrew was listening.
Related Commentaries of Genesis 18:10
Genesis 18:10
10 And he said, I will certainly return unto thee according to the time of life; and, lo, Sarah thy wife shall have a son. And Sarah heard it in the tent door, which was behind him.