'Sabbath day' in the Bible

And they go into Capernaum; and straightway on the sabbath day he entered into the synagogue and taught.

And it came to pass, that he was going on the sabbath day through the grainfields; and his disciples began, as they went, to pluck the ears.

And the Pharisees said unto him, Behold, why do they on the sabbath day that which is not lawful?

And they watched him, whether he would heal him on the sabbath day; that they might accuse him.

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.