Job compares his brothers to a brook that disappears and fails travelers who expected water (Job 6:15–17). He says they see his terror and are afraid, suggesting they have become a disappointment in his need (Job 6:21).
Job says a suffering person should receive loyal kindness from friends, even when that person’s spiritual grip seems to be slipping. Instead, Job claims his “brothers” have failed him like seasonal desert streams: they look promising when fed by ice and snow, but disappear when travelers most need water. These verses sit inside Job’s first long reply to Eliphaz (Job.6.1-Job.7.21). After describing how crushing his pain feels, Job defends the sharpness of his speech as the sound of real anguish. He then pivots from talking about his suffering to addressing how his friends are treating him.
Job assumes friendship carries a moral duty: when someone is at the point of collapse, loyal kindness is what they should receive (verse 14). The passage treats that duty as urgent, not optional. Job then explains his complaint with a desert image.
A careful answer keeps the immediate passage, the book's argument, and the whole-Bible storyline together, so the question is answered in context instead of as a detached idea.
Start with Job 6:15-17, then read the surrounding section so the answer stays connected to the passage's flow.
15My brothers have dealt deceitfully as a brook, As the channel of brooks that pass away;
16Which are black by reason of the ice, in which the snow hides itself:
17In the dry season, they vanish. When it is hot, they are consumed out of their place.