The Waqifites' and Their Doctrines

I just found out that the cause/reason behind appearance of Waqifites had to do with usurping of the Khums.

Imam Musa al-Kadhim (as) appointed a few agents to manage khums. After a while and unknowingly, these agents started using the community wealth for personal use. When Imam Musa (as) died, his successor, our eight Imam ar-Redha (as) requested the khums to be sent to him. These agents declined by claiming that Imam Musa al-Kadhim (as) did not die in the prison.

The Waqifities maintained that Imam Musa b. Ja‘far, peace be on him, was alive, did not die, and would never die, that he was raised to the heaven just as al-Masïh b. Maryam was raised, and that he was the awaited one who would undertake (the office of the Imamate, al-qa’im) and fill the world with justice and fairness as it was filled with oppression and tyranny. They claimed that the one who was in the prison of al-Sindi was not Imam Musa, peace be on him, rather the people imagined that he was in prison.

Taken from ImamReza.net