Sforno on Genesis 45:12/ספורנו על בראשית מ״ה:י״ב

1ועיני אחי בנימין, who had been unaware that Joseph had been sold.

2כי פי המדבר אליכם, without the need of an interpreter. At the time when I had been sold, no one spoke our language except our family. The buyers were Ishmaelites and Midianites, each with their own language