Charles Ellicott Commentary Lamentations 2:17

"Jehovah hath done that which he purposed; he hath fulfilled his word that he commanded in the days of old; He hath thrown down, and hath not pitied: And he hath caused the enemy to rejoice over thee; he hath exalted the horn of thine adversaries." — Lamentations 2:17 (ASV)

The Lord has done ... —The writer points, in opposition to the boasts of the enemies, to the true author of the misery of the people. In that thought, terrible as it might at first seem, there was an element of hope. It was better to fall into the hands of God than into those of men (2 Samuel 24:14). The suffering came as a chastisement for past transgressions, and might therefore be mitigated by repentance. The Destroyer was also the Healer, and would answer the prayers of those who called on Him.