From a letter by shaykh Muhammad ibn Ali al-Sanusi (may Allah be pleased with him and please him).
For him who wants our Way of Proofs (tareeqatnua al-burhaaniyya), we have ordered what our teacher (Ahmad ibn Idris) has ordered all of the brothers: To stick to reading the likes of:
Sahih Bukhari, the Muwatta, and Bulugh al-Maram in Hadith.
The Risala of Ibn Abi Zaid in Fiqh.
And reading the seven Sufi treatises, which are:
The Raa’iyya (A poetic version of Suhrawardi’s Awarif al-Ma’arif by his student al-Sharishi), the Haa’iyya, and al-Mabaahith al-Asliyya (of Ibn al-Banna al-Sarqasti – there is a commentary on it by Ibn Ajiba), which are purely on sulook (travelling the path) and virtuous character;
Al-Hatimiyya (possibly the aphorisms of Ibn Arabi: al-Hikma al-Hatimiyya), al-Raslaniyya (of Raslan al-Dimashqi), and al-Fusus (of Ibn Arabi), which are purely on Gnosis (irfan).
And the barzakh between them is the Hikam of Ibn Ata’Allah al-Sakandari…
For it is not permissible for anyone to embark upon anything without knowing God’s ruling on the matter and its proof. For in the first two are more than 1600 and 1700 sahih hadiths that cover all matters, and in the Risala [of Ibn Abi Zaid] about four thousand hadiths as well, 600 of which in the wording of the Prophet and 3400 in their meaning…. As for the seven books mentioned, they are the quintessence of that which is related to the station of Ihsan and that which leads to it from the two stations that come before ‘Worship God as if you see Him, for if you do not see Him then He sees you.’ You will find your share in that according to your capabilities.
And stay away from those who tell you not to place too much importance on knowledge, and have no knowledge of what the best of the people of Allah are like. For they are in two groups: ishraaqiyya and burhaaniyya. As for the former, their habit is that of purifying their souls from disturbances, and guiding them towards al-Haqq so that they are granted gnosis and secrets without learning or studying, in the way of: And have taqwa of Allah and Allah will teach you (Qur’an 2:282). As for the latter, their habit is the following of the commandments and the avoidance of that which is forbidden, and acquiring the four sciences that are: Knowledge of the Essence and the Attributes, Fiqh, Hadith, and the aalaat (the sciences like grammar, logic, and rhetoric that are necessary tools for the other sciences), as is shown by al-Shadhili and Zarruq, may God be pleased with them.
And the way of our teacher (Ahmad ibn Idris) may God be pleased with him combines them both. So he who wants the ishraaqiyya travels on its path, and he who wants the burhaaniyya travels upon its path, and it is the one that dominates [our teacher’s] states because it is the best of the two paths, in that it was the dominant state of the Prophet, peace be upon him, and most of his companions.
Note: For those who want to benefit from the Ra’iyya of al-Sharishi, Chapter Six of the Ibriz is dedicated to commentary on its lines about the qualities of the shaykh and the disciple. See: Ahmad b. al-Mubarak al-Lamati, Pure Gold from the Words of Sayyidi Abd al-Aziz al-Dabbagh. Translated by O’Kane and Radtke.