your eyes see, and the eyes of my brother Benjamin

The word "eyes" stands for the entire person. Alternate translation: "All of you and Benjamin can see" (See: rc://en/ta/man/jit/figs-synecdoche)

that it is my mouth that speaks to you

The word "mouth" stands for the entire person. Alternate translation: "that I, Joseph, am speaking to you" (See: rc://en/ta/man/jit/figs-synecdoche)