forty nights upon Mt. Sinai

وَإِذْ وَٰعَدْنَا مُوسَىٰٓ أَرْبَعِينَ لَيْلَةً ثُمَّ ٱتَّخَذْتُمُ ٱلْعِجْلَ مِنۢ بَعْدِهِۦ وَأَنتُمْ ظَـٰلِمُونَ

We appointed forty nights for Moses [on Mount Sinai] and then, while he was away, you took to worshipping the calf- a terrible wrong.

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

We appointed thirty nights for Moses, then added ten more: the term set by his Lord was completed in forty nights. Moses said to his brother Aaron, ‘Take my place among my people: act rightly and do not follow the way of those who spread corruption.’