Rabbi Elazar interpreted Joseph's reference to Benjamin in to mean that just as Joseph bore no malice against his brother Benjamin (who had no part in selling Joseph to Egypt), so Joseph had no malice against his other brothers. And Rabbi Elazar interpreted Joseph's reference to his mouth in to mean that Joseph's words reflected what was in his heart. A Midrash interpreted Joseph's reference to his mouth in to mean that Joseph asked them to note that he spoke in Hebrew.