Know now that God - Understand the case; and in order that they might, he goes into an extended description of the calamities which God had brought upon him. He wished them to be “fully” apprised of all that he had suffered at the hand of God.
Hath overthrown me - The word used here (עות ‛âvath) means to bend, to make crooked or curved; then to distort, prevert: them to overturn, to destroy; Isaiah 24:1; Lamentations 3:9. The meaning here is, that he had been in a state of prosperity, but that God had completely “reversed” everything.
And hath compassed me with his net - Has sprung his net upon me as a hunter does, and I am caught. Perhaps there may be an allusion here to what Bildad said in Job 18:8 ff, that the wicked would be taken in his own snares. Instead of that, Job says that “God” had sprung the snare upon him - for reasons which he could not understand, but in such a manner as should move the compassion of his friends.