أو كونه عالما به
Or to make the addressee aware that the speaker knows the judgment.
Sometimes the addressee already knows the proposition, but does not know that the speaker knows it too. A report may then supply lāzim fāʾidat al-khabar, knowledge of the speaker’s awareness.
You know that you studied today. Your teacher says «قَرَأْتَ الْكِتَابَ الْيَوْمَ». The event is not new to you; what is new is that the teacher knows about it.
This explains the familiar aim of such an utterance, not a claim that the benefit is invariably gained in every instance.