وَوَٰعَدۡنَا مُوسَىٰ ثَلَٰثِينَ لَيۡلَةً وَأَتۡمَمۡنَٰهَا بِعَشۡرٍ فَتَمَّ مِيقَٰتُ رَبِّهِۦٓ أَرۡبَعِينَ لَيۡلَةً ۚ وَقَالَ مُوسَىٰ لِأَخِيهِ هَٰرُونَ ٱخۡلُفۡنِى فِى قَوۡمِى وَأَصۡلِحۡ وَلَا تَتَّبِعۡ سَبِيلَ ٱلۡمُفۡسِدِينَ
We appointed for Moses thirty nights, and completed (the period) with ten (more): thus was completed the term (of communion) with his Lord, forty nights. And Moses had charged his brother Aaron (before he went up): "Act for me amongst my people: Do right, and follow not the way of those who do mischief."<br/>
And We appointed (read wa-waa'adnaa or wa-wa'adnaa) for Moses thirty nights, at the end of which We would speak to him, after he has fasted [during that period]; that was the month of Dhoo'l-Qa'da. He completed the fast. But when it came to an end, he disliked the [bad] odour of his mouth and so cleaned his teeth. God then commanded him [to fast for] another ten nights so that He may speak to him despite the odour in his mouth: as God says, and completed them with ten, nights of Dhoo'l-Hijja. Thus was the time appointed by his Lord concluded, the time at which God had promised him to speak to him, as forty (arba'eena is a circumstantial qualifier) nights (laylatan is for specification); and Moses said to his brother Aaron, when he was departing to the Mount for the communion [with his Lord]: 'Succeed me, be my deputy, over my people, and be righteous, [among them] with regard to their affair, and do not follow the way of the agents of corruption', by consenting with them to acts of disobedience.