How sound are the statements attributed to Amr ibn Dinar, Abu al-Shatha, Ibn Abbas, Ahmad ibn Hanbal, Ibn Hazm, and Al-Shawkani regarding the permissibility of masturbation? What is the refutation of their evidence, especially considering the objection to using the verse: "And those who guard their private parts" as proof, and the assertion that the default ruling is permissibility unless there is definitive evidence of prohibition, taking into account what modern medicine has established regarding the health harms resulting from addiction to this habit?

The relied-upon position in the Hanbali madhhab (definition) is that masturbation is forbidden (haram (definition)), and this is the view of the majority of the Ummah. The narrations attributed to Ibn Abbas and Ibn Umar regarding both permissibility and impermissibility are questionable. However, detestability (karahah) is authentically reported from 'Ata', while absolute permissibility is authentically reported from Al-Hasan (definition), Amr ibn Dinar, Ziyad Abi Al-Ala, and Mujahid. Both Imam Malik and Al-Shafi'i used the noble verse as evidence for its prohibition, and this is a sound deduction. One should not rely solely on medical evidence for prohibition, but rather on legal (Sharia (definition)) proofs.