«فَمَنْ أَعْدَى الْأَوَّلَ؟»
Who, then, infected the first one?
The question reminds the hearer that disease cannot depend on an endless sequence of earlier infected persons. The first case occurred under God's decree and created causes; later cases remain subject to the same sovereignty.
It does not cancel the precautionary instruction in the other report. Rather, it counters the mistaken assumption that a secondary cause acts independently and without qualification. Recognizing a cause and attributing autonomous power to it are distinct.