Do teachers who command their students to abandon sins that they themselves commit fall under the Almighty’s saying: (Do you enjoin righteousness upon people and forget yourselves), and does that prevent them from advising students?

The general principle is that a preacher should not contradict what he forbids. However, regarding the question of whether enjoining good and forbidding evil is waived if a person does not practice it himself, there are two scholarly opinions. The correct view is that it is not waived, because enjoining good is an obligation even if the person falls short in their own practice. The verse, "Do you enjoin righteousness upon the people and forget yourselves?" (2:44) condemns them for abandoning the performance of righteousness, not for enjoining it. It is preferable for a scholar to practice what he preaches.