Midrash su Geremia 50:25

Rabbi Pinchas said in the name of Rabbi Hoshaya: Even though it says: "for thereon He abstained from all His work", He abstained from the work of [creating] His world, but He did not abstain from the work on the wicked and not from the work on the righteous, but He labours with them both. He shows both the wicked and the righteous the nature [or: a semblance] of their designs. From where [do we know] that the punishment of the wicked is called "work"? From what is said in Jer. 50:25: "The Eternal One opened His armoury and brought out the weapons of His wrath; surely that is work." And from where [do we know] that the reward of the righteous is called "work"? From what is said in Ps. 31:20: "How great is Your goodness that You store up for those who fear You; You labour for those who take refuge in You in the sight of the sons of men."

R. Phinehas stated in the name of R. Joshua: Though it is written concerning Him that He rested from all His labors, it indicates merely that He rested from the work of creation, but not that He rests from considering the deeds of the righteous and the acts of the wicked. Rather, He works with them. He reveals to these (the righteous) the essential character of their deeds and to those (the wicked) the essential nature of their acts. How do we know that the punishment of the wicked is called work? It is said: The Lord hath opened His armory and hath brought forth the weapons of His indignation; for it is a work that the Lord God of hosts hath to do (Jer. 50:25). How do we know that rewarding the righteous is considered work? It is said: Oh, how abundant is Thy goodness, which Thou hast laid up for them that fear Thee; which Thou has wrought for them (Ps. 31:20).