What invalidates the fast by being introduced into the body cavity?

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The fast is broken by everything intentionally introduced into the interior of the body, such as the stomach, throat, or any hollow passage reaching the stomach, provided it was introduced by choice and could have been avoided. This applies whether introduction is through the usual route (the mouth) or unusual routes like forced feeding (wajur) or administering medicine into the throat (laddud). It also applies if introduced via the nose (snuffing/sa'ut), through the ear to the brain, through the eye to the throat (like kohl/surma), via the anus through enema (hiqna), or through treatment for a deep wound (ja'ifah) reaching the stomach, or treatment for a head wound (ma'mūmah) reaching the brain. This invalidates the fast because it reaches the interior of the body intentionally, resembling eating. Similarly, if one wounds oneself or is wounded by another intentionally, and the substance reaches the stomach, whether it remains there or exits, the fast is broken. This view is held by Al-Shafi'i.