Genesis 44:5 - Matthew Poole's English Annotations on the Holy Bible

Amongst the several kinds of divination in use among the Egyptians and other heathens, this was one, to do it by a cup or bason, which they filled with water, and put in them plates of silver, or precious stones, in which certain characters were engraven, by which, and some words they used, they called upon the devil, who gave them answer. Joseph did not use this course, nor was a diviner, but the people thought him such a one, and the steward might represent him as such, for the better covering or carrying on his design. But this sense agrees not with Genesis 44:15, Wot you not, & c. Which words show that he speaks of something which they all might easily know; but they did not know that Joseph was a diviner, much less that he divined by that cup, whereas that kind of divination was generally performed by a glass, not by a cup. Others observe, that the Hebrew word ofttimes signifies not to divine, but only to observe and discover a thing, as Genesis 30:27 1 Kings 20:33, and render the place thus, whereby he will certainly observe or discover, to wit, what you are and do. But this also seems not to consist with Genesis 44:15, and the supplement is too large and remote. The true sense then is this, the Hebrew bo is not to be rendered by which, but concerning which, as the particle beth is oft used, and it notes not the instrument whereby, but the object about which, he did divine, and the words must be rendered, concerning which he can or would certainly divine. And this agrees well with Genesis 44:15: q.d. Did you think you could deceive my master? Did not you and all others know that he could divine, and discover secret things, whence he had both his name and preferment? And this cup being much prized and used by him, you might easily judge that he would use his art to recover it. Ye have done evil, i.e. very evil, unjustly, unthankfully, and foolishly.