Charles H. Spurgeon on Psalms 79:12

"Render unto our neighbours sevenfold into their bosom," etc. This may seem to be contrary to common justice; because that the punishment should not exceed the fault. But here you are to know, that this hath not respect unto what the enemies of God's church have acted, but what they have deserved. And therefore when the prophet here says, "Render unto our neighbours sevenfold," it is not sevenfold beyond their deserts; for one scorn that a wicked man poureth upon a child of God (and so upon God), cannot be recompensed with ten thousand reproaches poured upon wicked men. The least reproach poured upon God is an infinite wrong. And the reproach of his people is so much his, as he reckons it as his own; and will therefore render to their enemies their reproach "sevenfold" (and that's but equal) "into their bosom."—Abraham Wright.