In this verse the responsible priest is given his sentence: he will stumble, so as not to rise again. In his fall he will drag the prophet along. A prophet also had to lead, pass on God’s words to the people. But that did not happen. He pleased the people. He too will fall in the night. Both priest and prophet fall. If it is not during the day (thus when you have enough light to avoid tripping), then it is at night. It does not matter: all spiritual leaders in Israel fail and fall.
5 You shall stumble by day; the prophet also shall stumble with you by night; and I will destroy your mother.