Verse 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 We granted an audience to Moses for thirty nights and completed it by adding ten; he therefore spent a period of time totaling forty nights at his Lord. And Moses said to his brother Aaron you shall serve as my substitute amongst my people and maintain righteousness and do not follow the ways of the wicked.