Ia adalah ilmu tentang kaedah-kaedah yang dengannya diketahui keadaan sanad dan matan hadis. Tujuannya ialah membezakan hadis sahih daripada yang lain. Ia terbahagi kepada dua jenis: ilmu hadis yang berkaitan dengan periwayatan [riwāya] dan ilmu hadis yang berkaitan dengan maksud [dirāya]. Adapun ilmu yang berkaitan dengan periwayatan, ia merangkumi periwayatan kata-kata Nabi ﷺ, perbuatan, persetujuan dan sifat baginda, dari segi penyampaiannya, ketepatannya dan penulisan lafaz [tahrīr alfādh]. Adapun ilmu yang berkaitan dengan maksud, melaluinya diketahui hakikat, syarat, jenis dan hukum periwayatan, serta keadaan para perawi, sifat-sifat mereka, jenis-jenis periwayatan dan perkara yang berkaitan dengannya. Dirāya juga merangkumi pengetahuan tentang maksud yang terkandung dalam hadis, sama ada ia bertentangan dengan nas yang qat'i atau tidak.

It is the science of those laws whereby the condition of the sanad [chain of transmission] and matn [text of the ḥadīth] is known. Its objective is to differentiate the sahīh hadīth from the others. It is of two types: the science of hadīth pertaining to transmission [riwāya] and the science of the hadīth pertaining to meaning [dirāya]. As for the one pertaining to transmission, it includes the transmission of the sayings of the Prophet , his actions, consent and attributes, with repsect to their narration, accuracy and transcription of words [tahrīr alfādh]. As for the one pertaining to the meaning, the reality, conditions, types and rules of transmission are known through it, as well as the state of the transmitters, their conditions, the types of the transmissions and that which is related to it. Dirāya also covers knowledge of the meaning contained in the hadīth in terms of whether it contradicts a definitive text.