الْقَافِلَةُ سَالِمَةٌ. لَمْ يُصِبْهَا سُوءٌ.
The caravan is safe. No harm befell it.
The second clause can reinforce and clarify the first: “safe” is explained in terms of absence of injury. By contrast, “They stayed in the valley. The fog was dense” most naturally answers why they stayed.
Faṣl may occur in both, but for distinct reasons. One depends on close semantic unity; the other on an implicit question and response. What matters is the actual function of each clause.