The Pulpit Commentary - Genesis 42:8
And Joseph knew his brethren, but they knew not him . The lapse of time since the tragedy of Dothan, twenty years before, the high position occupied by Joseph, the Egyptian manners he had by this time assumed, and the strange tongue m which he conversed with them, all conspired to prevent Jacob's sons from recognizing their younger brother; while the facts that Joseph's brethren were all grown men when he had last looked upon them, that he was quite familiar with their appearances, and that... read more
The Pulpit Commentary - Genesis 42:7
And Joseph saw his brethren, and he knew them, but (literally, and) made himself strange unto them . The root נָכַר , to be marked, signed, by indentation, hence to be foreign (Furst), or simply to be strange (Gesenius), in the Hiphil signifies to press strongly into a thing (Furst), to look at a thing as strange (Gesenius), or to recognize, and in the Hithpael has the sense of representing one's self as strange, i.e. of feigning one's self to be a foreigner. And spake roughly unto... read more