Shaykh Ahmad al-Tijani (God be pleased with him) said:

Whoever rises up to the creation, calling them to God (Exalted is He), after having been granted special permission from God, his words will enter every heart and he will find acceptance among the creation and a response to his call. His commands will be obeyed by the creation and his prohibitions avoided. And he will be obeyed and his words will be sweet to the hearts.

But if someone rises up to call the creation to God with a general permission, without having been granted special permission, his words will not benefit. And he will not find acceptance. And the tongue of the Real will say to him, with the speech of the state [lisan al-hal] in the realm of the Realities, “We have not commanded you to do that. Nor are you worthy. Rather, you are being meddlesome.” And anyone who is in that position will be tested with the machinations of his ego, such as [desire for] leadership and chicanery. He will not receive anything from God.

And if anyone falsely claims to have special permission to call to God [i.e., claiming to be a Shaykh of Tarbiyya] and comes out to the creation calling them, he will die as a disbeliever, unless he repents. We ask God for safety and well-being by the rank of the Prophet (God bless him and give him peace) and his Family.