How to reconcile the hadiths "Flee from the leper" and "There is no contagion"

The questioner : O Shaykh, how do you reconcile the two hadiths

The Shaykh : Yes, the reconciliation between his saying (peace and blessings be upon him) and his saying is that upon reflection, there is no contradiction between them. The first hadith, "Flee from the leper," means that the Prophet (peace and blessings be upon him) intended for a person to avoid the causes of danger. The second hadith intended to clarify that if contagion were to occur, this contagion, by the permission of Allah, is not as the Arabs believed it to be, spreading by itself, but rather it is by the command of Allah (Mighty and Majestic). Thus, the negation in his saying is a negation of its effect except by the permission of Allah, not a negation of its existence. Indeed, contagion exists, and everyone knows that some diseases are highly contagious.