Is There a Permissible Sufism?

The Book (i.e., the Quran) and the Sunnah are not called Sufism, but they are called the knowledge of the Book (Quran) and the Sunnah. As for Sufism, its principle is asceticism. The principle of Sufism is strictness in asceticism and worship, then it evolved into phases that reached the point of atheism and the belief in the unity of existence (i.e., Allah is literally everywhere). And this is the result of the one who goes against the Quran and Sunnah, even if at the beginning he intended to do good. It is obligatory to limit oneself to the Quran and the Sunnah, for they are sufficient. Worship is only in accordance with the Quran and Sunnah, and piety is also only in accordance with the Quran and Sunnah.