Gen 39:19-20
Joseph in Prison. - Potiphar was enraged at what he heard, and put Joseph into the prison where (אשׁר for שׁם אשׁר, Gen 40:3 like Gen 35:13) the king’s prisoners (state-prisoners) were confined. הסּהר בּית: lit., the house of enclosure, from סהר, to surround or enclose (ὀχύρωμα, lxx); the state-prison surrounded by a wall. This was a very moderate punishment. For according to Diod. Sic. (i. 78) the laws of the Egyptians were πικροὶ περὶ τῶν γυναιῶν νόμοι. An attempt at adultery was to be punished with 1000 blows, and rape upon a free woman still more severely. It is possible that Potiphar was not fully convinced of his wife’s chastity, and therefore did not place unlimited credence in what she said.
But even in that case it was the mercy of the faithful covenant God, which now as before (Gen 37:20.) rescued Joseph’s life.