Charles Ellicott Commentary John 9:20

"His parents answered and said, We know that this is our son, and that he was born blind:" — John 9:20 (ASV)

We know that this is our son . . .—The two earlier questions of matter of fact they can answer with certainty. They know, as none besides themselves can know, that he was their son, and they know the painful truth that he was born blind.