Which two tribes did Joab leave out of David's census, finding the king's order detestable?

Answer: Levi and Benjamin

1 Chronicles 21:6 says Joab did not include Levi and Benjamin in the count, because the king's command was detestable to him.

“But Joab did not include Levi and Benjamin in the count, because the king’s command was detestable to him.”— 1 Chronicles 21:6 (BSB)