Good is always legal.

Going on from that place, he went into their synagogue, and a man with a shriveled hand was there. Looking for a reason to accuse Jesus, they asked him, "Is it lawful to heal on the Sabbath?" He said to them, "If any of you has a sheep and it falls into a pit on the Sabbath, will you not take hold of it and lift it out? How much more valuable is a man than a sheep! Therefore it is lawful to do good on the Sabbath."
--Matthew 12:9-12