What is the science of reality (or truth)?

There is nothing in Islamic sciences called "the science of reality" (ʿilm al-ḥaqīqah). Sufis divide the sciences of religion into the science of Sharia, which is the science of the outward (ẓāhir), and the science of reality (ʿilm al-ḥaqīqah), which is the science of the inward (bāṭin). They claim that the science of reality is the knowledge of Al-Khidr and the science of Sharia is the knowledge of Musa, and that they receive inward knowledge directly from Allah. Scholars have ruled that whoever says this is guilty of disbelief (kufr) and heresy (zandaqah). So, whoever says that reality contradicts Sharia, or that the inward contradicts the outward, is closer to disbelief. And whoever believes that there is a path to Allah for anyone other than following Muhammad, peace be upon him, or says: "I need him for outward knowledge but not for inward knowledge, or for the science of Sharia but not for the science of reality," has disbelieved.