And We appointed for Musa (Moses) thirty nights and added (to the period) ten (more), and he completed the term, appointed by his Lord, of forty nights. And Musa (Moses) said to his brother Harun (Aaron): "Replace me among my people, act in the Right Way (by ordering the people to obey Allah and to worship Him Alone) and follow not the way of the Mufsidun (mischief-makers)."