What is the ruling of Islamic law on Sufism, and the ruling on following the path of a specific shaykh within it, and was Umar ibn Abd al-Aziz a Sufi?

The Sharia ruling on Sufis varies depending on their state; the Sufis of the old era (the time of Al-Junayd) differed from Sufis in later eras, into which extremism and innovation entered. Following a specific shaykh is not obligatory, and this is indicated by the fact that the Tabi'un (followers) and junior Companions benefited from whomever they could receive knowledge from, without blindly imitating one specific individual. As for Umar ibn Abd al-Aziz, he was the epitome of uprightness, piety, and asceticism. He associated with scholars, and nothing is known of him except his adherence to the two revelations (Quran and Sunnah) and the guidance of the Companions and the Tabi'un.