The tradition of trial is regarded as one of God`s general traditions. This tradition happened during the absence of Moses (a). As is understood by Quranic verses, Bani Esrael`s weak belief, mischief-makers among them and affection of Egyptian culture on them demanded a ground to distinguish true believers from hypocritical people and clean the effects of Egyptian culture from their mind. The ground was a Divine trial in the form of lengthening Moses` Divinely determined time of appointment from thirty nights to forty and appearance of a golden statue like a calf made by Samiri. in this trial Bani Israel failed because of hurry, little use of reason`s guidance and weakening and leaving Harun (a) and turning to worshiping a calf were misled. The trial is considerable with regard to its quality, quantity and time. Though it should be stated that moses` measures and Bani Esrael`s repentance led to desirable ends.