Genesis 43:28 - Joseph Benson’s Commentary on the Old and New Testaments

When they brought him the present, they bowed themselves before him, and again, when they gave him an account of their father's health, they made obeisance, and called him, Thy servant, our father Thus were Joseph's dreams fulfilled more and more; and even the father, by the sons, bowed before him. Probably Jacob had directed them, if they had occasion to speak of him to the man, the lord of the land, to call him his servant.