﴿ ۞ وَوَٰعَدْنَا مُوسَىٰ ثَلَٰثِينَ لَيْلَةًۭ وَأَتْمَمْنَٰهَا بِعَشْرٍۢ فَتَمَّ مِيقَٰتُ رَبِّهِۦٓ أَرْبَعِينَ لَيْلَةًۭ ۚ وَقَالَ مُوسَىٰ لِأَخِيهِ هَٰرُونَ ٱخْلُفْنِى فِى قَوْمِى وَأَصْلِحْ وَلَا تَتَّبِعْ سَبِيلَ ٱلْمُفْسِدِينَ ﴾

“AND [then] We appointed for Moses thirty nights [on Mount Sinai]; and We added to them ten, whereby the term of forty nights set bye, his Sustainer was fulfilled. And Moses said unto his brother Aaron: "Take thou my place among my people; and act righteously, and follow not the path of the spreaders of corruption."”

(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.