Qur'an 7:142

۞ وَوَٰعَدْنَا مُوسَىٰ ثَلَـٰثِينَ لَيْلَةً وَأَتْمَمْنَـٰهَا بِعَشْرٍ فَتَمَّ مِيقَـٰتُ رَبِّهِۦٓ أَرْبَعِينَ لَيْلَةً ۚ وَقَالَ مُوسَىٰ لِأَخِيهِ هَـٰرُونَ ٱخْلُفْنِى فِى قَوْمِى وَأَصْلِحْ وَلَا تَتَّبِعْ سَبِيلَ ٱلْمُفْسِدِينَ

And when We did appoint for Moses thirty nights (of solitude), and added to them ten, and he completed the whole time appointed by his Lord of forty nights; and Moses said unto his brother, Aaron: Take my place among the people. Do right, and follow not the way of mischief-makers.