John Calvin Commentary Isaiah 13:6

"Wail ye; for the day of Jehovah is at hand; as destruction from the Almighty shall it come." — Isaiah 13:6 (ASV)

Howl ye. He continues the same argument and commands the inhabitants of Babylon to howl. Not that he directs instruction to them, as if he hoped that it would be of any advantage, but, in foretelling what their condition will be, he emphatically employs this form of direct address.

For the day of the Lord is at hand. He calls it the day of the Lord, according to the usual custom of Scripture, because when the Lord delays his judgment, he appears to cease from the discharge of his office, like judges when they do not ascend the judgment seat. This manner of expression is noteworthy, for we would gladly subject God to our disposal, so that he might immediately pass sentence against the wicked. But he has his own appointed time and knows the seasons when it is proper both to punish the bad and to assist the good.

It shall come as destruction from the Strong One. He threatens that the severity of judgment will be such that the inhabitants of Babylon will have good reason not only to cry but to howl, because God displays his power to lay them waste and destroy them. שדד (shadad) signifies to lay waste and plunder. From this verb is derived שדי (Shaddai), one of the names of God, which some render Almighty. There is therefore an elegant allusion to the derivation of the word, as if he had said that the inhabitants of Babylon will learn by their own destruction how appropriately God is called שדי (Shaddai), that is, strong and powerful to destroy.