Do you say needn't or shouldn't?

"Think in terms of saying "needn't" instead of "shouldn't". "Shouldn't" is the language of legalism and legalism is never good news. But the gospel not only tells us what we should and shouldn't do, it also gives us the motives and resources to live the good life. It offers us a bigger and better life than the false promises of sin. So we can say more than "I shouldn't lie at work". We can say "I needn't lie at work, because I have a Father in heaven who cares for me" or "I don't need to prove myself, because I have God's approval in Christ"."

Tim Chester, Gospel Centred Work