Shaykh is fasting the 11th of Muharram established from the Sunnah of not? The 9th and 10th are clearly established, but regarding the 11th, scholars have differed. Shaykh Abdul ar Rayyis & others did not consider it established, while Shaykh Aziz farhan & others consider it. Which view is correct?

Ustadh AbdulAziz al-Haqqan
Shaykh Ibn Baz (rahimahullah) says if you fast the 10th and the 11th, then it is correct.