Jeremiah 23:5-8; Ps 72(71):1-2. 12-13. 18-19; Matthew 1:18-24
Jeremiah and Ezekiel are the prophets to he Exile. Israel is removed from the promised land, but the prophets show that the Lord will return to save them. This Lord is given the name 'righteous', or may be translated as 'Saving Justice'.
Saving Justice can have different levels of meaning - from the superficial human one - that if you are in the right, justice will save you, to the deeper meaning of fidelity of God to his covenant promises. These of course also require our fidelity - a covenant is two way. Another view of 'Saving Justice' is the concept that we call 'Grace'. Grace is the saving love of God, given freely to all who all accept it, most often through our sacramental life.
However it works for you today - the prophet promises that the saving justice will come. It will come with the Lord - and we know, as Christians, that this has happened and is a reality in our daily lives.