Job 36:9 (ESV)

9 then he declares to them their work and their transgressions, that they are behaving arrogantly.

When God brings suffering over his own people, it is to show them their sin, especially their arrogance (a sin that Elihu sees in Job’s own life, Job 33:17). Elihu has already referred to the chastisement of a sickbed (Job 33:19–26). Now he broadens God’s chastisement to include all kinds of affliction (Job 36:8).