A.T. Robertson Commentary Mark 3:4

"And he saith unto them, Is it lawful on the sabbath day to do good, or to do harm? to save a life, or to kill? But they held their peace." — Mark 3:4 (ASV)

But they held their peace (ο δε εσιωπων). Imperfect tense. In sullen silence and helplessness before the merciless questions of Jesus as the poor man stood there before them all. Jesus by his pitiless alternatives between doing good (αγαθοποιεω, late Greek word in LXX and N.T.) and doing evil (κακοποιεω, ancient Greek word), to this man, for instance,

to save a life or to kill (ψυχην σωσα η αποκτεινα), as in this case. It was a terrible exposure.