It is in the qalb (the heart); love (maḥabba) for Allah, the Exalted, is in the qalb, and drawing near to Him is in the qalb. (Fath, 49)
Knowledge is sovereign over the intellect; the intellect does not have sovereignty over knowledge. Knowledge is only beneficial with the intellect, and the intellect is only beneficial with knowledge. (Ādāb, 23)
Sehl Abdullah (al-Tustarī) says: There are three types of knowledge: Knowledge min Allah (from Allah), which is the outward knowledge (ʿilm ẓāhir) that includes commands, prohibitions, rulings, and legal limits. Knowledge maʿa Allah (with Allah), which is knowledge that includes fear (khawf), hope (rajāʾ), love (maḥabba), and longing (shawq). Knowledge bi-Allah (by Allah), which is knowledge that includes the attributes of Allah. It has also been said that the outward knowledge (ʿilm ẓāhir) is the knowledge of the path (ṭarīq), and the inward knowledge (ʿilm bāṭin) is the knowledge of the destination (manzil). Furthermore, it has been stated that the inward knowledge (ʿilm bāṭin) is derived from the outward knowledge (ʿilm ẓāhir), and that any inward (bāṭin) knowledge not supported by the outward (ẓāhir) is bāṭil (invalid, false). (Ādāb, 25)
Knowledge is both an obligation (farīḍa) and a virtue (faḍīla). The obligatory (farīḍa) knowledge is that which a person must know in order to fulfill the duties of his religion. The virtuous (faḍīla) knowledge is the knowledge of the Book and the Sunnah.