The Lord does righteously in that He is benevolent towards the oppressed.
God’s will and way are made known to mankind.
This shows us that ‘slow to anger’ is to be taken positively.
To put this verse in different words for clarity:
He will not be angered by us to the bitter end, contending with us the whole way. He will not vent His wrath forever.
Good Justice
Protect the Innocent
Punish Evildoers
God's Justice
willingly - LXX - ἀπὸ καρδίας - from His heart
Consider the implications for our thankfulness.