Charles H. Spurgeon on Psalms 78:49

He cast upon them the fierceness of his anger, wrath, and indignation, and trouble. His last arrow was the sharpest. He reserved the strong wine of his indignation to the last. Note how the psalmist piles up the words, and well he might; for blow followed blow, each one more staggering than its predecessor, and then the crushing stroke was reserved for the end. By sending evil angels among them. Messengers of evil entered their houses at midnight, and smote the dearest objects of their love. The angels were evil to them, though good enough in themselves; those who to the heirs of salvation are ministers of grace, are to the heirs of wrath executioners of judgment. When God sends angels, they are sure to come, and if he bids them slay they will not spare. See how sin sets all the powers of heaven in array against man; he has no friend left in the universe when God is his enemy.