Al-A'raf 7:142

۞وَوَٰعَدۡنَا مُوسَىٰ ثَلَٰثِينَ لَيۡلَةٗ وَأَتۡمَمۡنَٰهَا بِعَشۡرٖ فَتَمَّ مِيقَٰتُ رَبِّهِۦٓ أَرۡبَعِينَ لَيۡلَةٗۚ وَقَالَ مُوسَىٰ لِأَخِيهِ هَٰرُونَ ٱخۡلُفۡنِي فِي قَوۡمِي وَأَصۡلِحۡ وَلَا تَتَّبِعۡ سَبِيلَ ٱلۡمُفۡسِدِينَ 142

And We made an appointment with Moses for thirty nights and perfected them by [the addition of] ten; so the term of his Lord was completed as forty nights. And Moses said to his brother Aaron, "Take my place among my people, do right [by them], and do not follow the way of the corrupters