ʿIlm al-Ladunnī (ladunnī knowledge) is the strongest and most unassailable of the acquired sciences attained through learning. (Risāla, 2)
ʿIlm al-Ladunnī is a knowledge in whose acquisition there is no intermediary between the servant and the Creator. It is like the light of the lamp of the unseen (ghayb). It is reflected upon a pure, empty, and subtle qalb (the heart). All sciences exist as known within the substance of the First and Universal Nafs (nafs, the lower self). This substance is related to the First Intellect (ʿAql) as the substance of Ḥawwāʾ is to Ādam, in the same way as the relation of pure, primary, and separate substances. (Risāla, 23)
ʿIlm al-Ladunnī is for the people of prophethood and walāya (walāya, sainthood), as was the case with Khidr. (Risāla, 24)
When Allah wills good for a servant, He lifts the veil between him and the nafs, which is like a tablet. There, in the tablet of the nafs, the secrets of certain beings become manifest. The meanings of those beings are inscribed there. The nafs expresses it as Allah wills for whomever He wills among His servants. The reality (ḥaqīqa) of wisdom is to attain ʿilm al-Ladunnī. Unless a person reaches this level, he cannot be the possessor of wisdom. For wisdom is a gift from Allah: "He gives wisdom to whom He wills, and whoever has been given wisdom has certainly been given much good. But none will remember except those of understanding" (al-Baqara 2:269). Those who reach the rank of ʿilm al-Ladunnī have no need to acquire many things or to spend time with the difficulty of learning. They learn little, but know much; they tire little, but rest much. (Risāla, 25)
The ulūm al-ladunniyya (ladunnī sciences) in the qalb (the heart) of the gnostics (ʿārifūn) who turn to Allah are, in fact, an allusion to a conversation in the Qur'an. To the one who turns to Allah with complete sincerity for forty days, controlling his nafs (the lower self) with an empty stomach, Allah opens the doors of ʿilm al-Ladunnī.
Although the sciences of practice (muʿāmala) are subtle and lofty, their loftiness, beauty, and delicacy are only so in comparison to the intellectual sciences, which are tainted by the judgment of rational consideration. This is something that surpasses the intellect. The light of the intellect is very clear and its mirror is purer. However, ʿilm al-Ladunnī, which is not dependent on action for its attainment, is nevertheless intertwined with action. The difference between the two is clear. For knowledge related to actions is the result of effort directed towards them, and thus comes according to one of its ranks. These are the sciences of felicity. The sciences I have informed you of are the ladunnī sciences, which cannot be tainted by the effort of the created (the rational) that requires absolute submission. Although the Real (al-Ḥaqq) has supported it (ta'yīd), the subtlety of one's striving later rises like a cloud over the mirror of the spirit (rūḥ). (Tadbīrāt, 207)