John Gill Commentary Genesis 44:27

"And thy servant my father said unto us, Ye know that my wife bare me two sons:" — Genesis 44:27 (ASV)

And your servant my father said to us
When thus pressed to let Benjamin go with them: you know that my wife bore me two [sons] ;
Rachel, by whom he had Joseph and Benjamin, and whom he calls his wife, she being his only lawful wife; Leah was imposed upon him, (Genesis 29:20–30) ; and the other two were concubines, (Genesis 30:4Genesis 30:9) .