لَوْ رَأَيْتَ مَا حَدَثَ...
If only you had seen what happened …
With the conditional response unspoken, the listener may imagine the magnitude of the event. In a frightening context the implied consequence differs from one of extraordinary joy. The ellipsis can intensify imagination or awe, yet the analyst should not supply one complete, supposedly original response without evidence.
Reconstructing possible meaning is different from claiming exact missing wording. The aim is to show what the context lets the listener infer, and what remains open because the speaker intentionally did not express it.