Did the Prophet, peace and blessings be upon him, deny contagion from the standpoint of human nature, experience, and ijtihad? And did Ibn al-Qayyim transmit this statement and favor it in his book "Miftah Dar al-Sa'adah"? And did the Prophet, peace and blessings be upon him, practice medicine based on experience and human nature?

Ibn al-Qayyim's summary regarding reconciling the two hadiths: "There is no contagion" and "Flee from the leper":

There are three approaches to understanding the hadith (definition): 1. What the Prophet informs about from revelation: This is infallible and corresponds to reality. 2. What the Prophet informs about based on his conjecture concerning worldly matters: This is not infallible, and an example is the pollination of date palms. Some scholars adopted this approach. 3. Affirming causes while purifying Tawhid (definition) (monotheism) (which is Ibn al-Qayyim's choice and the majority of scholars): The Prophet negated the belief of the polytheists in contagion as an independent cause that affects by itself without God's will. He affirmed the existence of causes that God has linked to their effects, and that they do not affect except by His permission and will. An example of this is his saying, "Let not one who has a sick camel bring it to one who has a healthy camel." The truth is to affirm causes while affirming the Oneness of God, without neglecting causes or associating partners with God through them.