Moses
Genesis 42:23ESV·traditional attribution

They did not know that Joseph understood them, for there was an interpreter between them.

Matthew Henry Presbyterian @wholebiblehenry

Here is, I. The penitent reflection Joseph's brethren made upon the wrong they had formerly done to him, Gen 42:21. They talked the matter over in the Hebrew tongue, not suspecting that Joseph, whom they took for a native of Egypt, understood them, much less that he was the person they spoke of. 1.

Commenting on Genesis 42:21-28

John Gill Reformed Baptist @doctorgill

And as one of them opened his sack,.... According to the Targum of Jonathan and Jarchi, this was Levi; but Aben Ezra thinks it is more likely to be Reuben the firstborn, who was one, that is, the first of them: to give his ass provender in the inn; at which they lay very probably the first night of their journey; a good man regards...

Adam Clarke Methodist @methodicalclarke

For he spake unto them by an interpreter - Either there was a very great difference between the two languages as then spoken, or Joseph, to prevent all suspicion, might affect to be ignorant of both. We have many evidences in this book that the Egyptians, Hebrews, Canaanites, and Syrians, could understand each other in a general way, though there are also proofs that there...