The Cup of Divination
The brothers still have no idea what is happening, but are as cooperative and humble as can be, neither of which seems to help them out much. Joseph frames his brothers with an egregious offense: the theft of the very goblet from which their gracious host had drunk.
When Joseph’s servant confronts the brothers for their alleged crime, he is told to ask, “Is not this [the cup] from which my lord drinks, and with which he indeed practices divination?” (verse 5). Did Joseph really use the cup for prognostication or the interpretation of omens? That would surely not have been approved of by God. About the cup of divination, the Jamieson, Fausset & Brown Commentary remarks: “Divination by cups, to ascertain the course of futurity, was one of the prevalent superstitions of ancient Egypt, as it is of Eastern countries still. It is not likely that Joseph, a pious believer in the true God, would have addicted himself to this superstitious practice. But he might have availed himself of that popular notion to carry out the successful execution of his stratagem for the last decisive trial of his brethren” (note on verse 5). In other words, Joseph may have allowed them to think he practiced divination with this cup to instill more fear in them—as it would look to them like they would be charged with the theft of something of great importance in Egypt.
Also notice that Joseph did not order his steward to tell a direct lie—rather, he simply told him to ask a question. The real answer would have been no. But the brothers didn’t know this.