I have been hired by Allah to get a wage, which if the space between the Earth and sky is filled up with pearls, still (the wage) would be more than it, for each of the questions I may answer you. Therefore, I deserve it that I must not feel tired or exhausted (in answering your questions).
"Bihar al-anwar" by al-'Allama al-Majlisi, ol.2, p. 3,