فَإِنْ كَانَ الْمُخَاطَبُ خَالِيَ الذِّهْنِ مِنَ الْحُكْمِ، أُلْقِيَ إِلَيْهِ الْخَبَرُ مُجَرَّدًا عَنِ التَّأْكِيدِ
If the listener has no prior judgment about the matter, the report is delivered without an emphatic marker.
This is the ibtidāʾī type of report. The hearer simply needs information, so there is normally no reason to open with an oath or several reinforcements.
Example: “أَخُوكَ قَادِمٌ.” Here “أَخُوكَ” is the subject of predication and “قَادِمٌ” its predicate. The message is complete without an independent emphatic particle.