as a sheep before her shearers is dumb
Isaiah 53:7 (KJV) He was oppressed, and he was afflicted, yet he opened not his mouth: he is brought as a lamb to the slaughter, and as a sheep before her shearers is dumb, so he openeth not his mouth.
Matthew 27:12 And when he was accused of the chief priests and elders, he answered nothing.
13 Then said Pilate unto him, Hearest thou not how many things they witness against thee?
14 And he answered him to never a word; insomuch that the governor marvelled greatly.