(And when We did appoint for Moses) to spend in the mountain (thirty nights (of solitude)) the month of the Dhu'l-Qa'dah, (and added to them ten) days from the month of Dhu'l-Hijjah, (and he completed the whole time appointed by his Lord of forty nights) as he promised; (and Moses said unto his brother: Take my place) be my deputy (among the people. Do right) enjoin them to do right, (and follow not the way of mischief-makers) by committing transgressions.