Deuteronomy 24:12-13

I always thought this was a little bit more difficult verse to understand, but what Christ intends is the principle of non-retaliation beyond physical insults to a level of legal and material disputes. This instruction challenges our instinct to defend ourselves and our possessions. In this teaching, Jesus advises that if someone sues you for your tunic (and by the way, the tunic was an undergarment, like a shirt or t-shirt, something like that, and which is not of great value), but if you are willing to give up your cloak—this is your outer garment—this is worth far more. And in fact, the cloak for many would be used as a blanket when they slept at night. So you can see how this would be a great loss to give up that as well, and that is what God wants us to do. This is mentioned in Exodus 22:26-27 and Deuteronomy 24:12-13. By this law, this outer garment was a possession that could be withheld, but not overnight.