Lamentations 3:60 "Thou has seen all their vengeance, all their devices against me."

Jeremiah is lamenting the destruction of Jerusalem, the punishment of the people, and the way he, who had been sent to warn them, has been treated. He acknowledges here, though, that God sees all, including his mistreatment. "Who has commanded, and it came to pass, unless the Lord ordained it?" he asks (Lamentations 3:37). And later he admits "Thou will requite them, O Lord, according to the work of their hands. Thou will give them dullness of heart; thy curse will be on them." (Lamentations 3:64–65).
 

Jeremiah is modeling abandonment to divine providence, or surrender, here. He knows that God is in charge and that nothing happens without His permission. The people's refusal to listen was known by God ahead of time (God even told Jeremiah that the people would not listen to him: "So you shall speak all these words to them, but they will not listen to you." (Jeremiah 7:27)). The suffering the people are going through was ordained by the Lord because He knew they would not listen, and the suffering and mistreatment of Jeremiah is also part of God's plan ("They will fight against you, but they shall not prevail against you." God said to Jeremiah at the outset of his mission (Jeremiah 1:19)).
 

Suffering is always difficult, especially when it seems unjust. Jeremiah did not deserve to be flung alive into a pit, with stones cast upon him and water poured in to cover his head (Lamentations 3:53–54), yet it happened, and God was with him through it ("I called upon thy name, O Lord, from the depths of the pit; thou didst hear my plea ... thou didst say "Do not fear!" (Lamentations 3:55–57)).  Having seen and experienced God's saving power, Jeremiah knows that God is always with him, always watching over him, and not letting him suffer anything that is not necessary to accomplish His purposes. When the people who rejected and persecuted Jeremiah come to their senses in the midst of their exile, they will have an unignorable, tangible example in Jeremiah of the effects of their sinfulness to contemplate. This will either bring them to repentance, or cause them to withdraw further into self-justification and sin. In the latter case, they will have the dullness of heart and the curse that Jeremiah describes, not because God is doing that to them, but because they are doing it to themselves; they are continuing to choose self, ego, and sin over repentance and mercy.

Jeremiah has been such a comfort to me over the last few years as unjust, and frankly wicked, treatment of so many has been so self-righteously proclaimed as good. It felt impossible to me that minds and hearts that so refused to see the harm they were perpetrating could be changed without great suffering, and that itself was a great suffering to me. But I came to realize, through Jeremiah and the rest of the Bible, and from reading things like Abandonment to Divine Providence and the Surrender Novena, that I have to surrender to God’s plan. That surrender has led me to see a little how God works. He chastises when He has to, but only to bring us back. When evil is great, His chastisements are also great, and they fall on the good and the wicked alike, just like the rain and the sun. But if we are close to Him, we will hear His "Do not fear" and  remember that He sees our suffering and all "their devices against" us, and His justice will not fail.