Taken from Nathan Klaus in, Pivot Patterns in the Former Prophets, Journal for the Study of the Old Testament Supplement Series 247, Sheffield, 1999
A. 31 And the king said unto him, Do as he hath said, and fall upon him, and bury him;
B. that thou mayest take away the innocent blood, which Joab shed, from me, and from the house of my father.
C. 32 And the LORD shall return his blood upon his own head,
D. who fell upon two men more righteous and better than he, and slew them with the sword,
E. my father David not knowing thereof,
D’. to wit, Abner the son of Ner, captain of the host of Israel,
and Amasa the son of Jether, captain of the host of Judah.
C’. 33 Their blood shall therefore return upon the head of Joab, and upon the head of his seed for ever:
B’. but upon David, and upon his seed, and upon his house, and upon his throne, shall there be peace for ever from the LORD.
A’. 34 So Benaiah the son of Jehoiada went up, and fell upon him, and slew him: and he was buried in his own house in the wilderness
Note: the record of the execution of Job highlights the innocence of David in the death of Abner and Amasa.