He remembers mercy

For I will cause Elam to be dismayed before their enemies and before those who seek their life. I will bring disaster upon them, My fierce anger, says the Lord;  and I will send the sword after them until I have consumed them. I will set My throne in Elam, and will destroy from there the king and the princes, says the Lord. But it shall come to pass in the latter days: I will bring back the captives of Elam, says the Lord.   Jeremiah 49:37-39

I will bring back…The Lord is fierce in judgement, yet in His wrath He remembers mercy.  Who is this God?