AL A'RAAF — Ayat 142
وَوَاعَدْنَا مُوسَى ثَلاَثِينَ لَيْلَةً وَأَتْمَمْنَاهَا بِعَشْرٍ فَتَمَّ مِيقَاتُ رَبِّهِ أَرْبَعِينَ لَيْلَةً وَقَالَ مُوسَى لأَخِيهِ هَارُونَ اخْلُفْنِي فِي قَوْمِي وَأَصْلِحْ وَلاَ تَتَّبِعْ سَبِيلَ الْمُفْسِدِينَ
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."
Tafsir Ibnu Katsir
وَوَعَدْنَا مُوسَى ثَلَـثِينَ لَيْلَةً وَأَتْمَمْنَاهَا بِعَشْرٍ فَتَمَّ مِيقَـتُ رَبِّهِ أَرْبَعِينَ لَيْلَةً وَقَالَ مُوسَى لاًّخِيهِ هَـرُونَ اخْلُفْنِى فِى قَوْمِى وَأَصْلِحْ وَلاَ تَتَّبِعْ سَبِيلَ الْمُفْسِدِينَ
142. And We appointed for Musa thirty nights and added ten, and he completed the term, appointed by his Lord, of forty nights. And Musa said to his brother Harun: â€Replace me among my people, act in the right way and follow not the way of the mischief-makers.'' Allah reminds the Children of Israel of the guidance that He sent to them by speaking directly to Musa and revealing the Tawrah to him. In it, was their law and the details of their legislation. Allah stated here that He appointed thirty nights for Musa. The scholars of Tafsir said that Musa fasted this period, and when they ended, Musa cleaned his teeth with a twig. Allah commanded him to complete the term adding ten more days, making the total forty. When the appointed term finished, Musa was about to return to Mount Tur, as Allah said,