Caution: Translations of Quran and Ḥadīth may lead to possible misapplications and misinterpretations. This site is intended for students of sacred knowledge that are proficient in comprehending classical Arabic and have a strong foundation in Islamic sciences. Also note that religious injunctions rely on several aspects beyond what one may glean through reading individual aḥādīth.
Qurʾān Bukhārī Muslim Nasāʾī Abū Dāwūd Tirmidhī Ibn Mājah Mālik Aḥmad Dārimī Ḥākim Ibn Ḥibbān Ṭabarānī Nasāʾī's Kubrá Bayhaqī al-Luʾluʾ wa-al-Marjān Ibn Rajab's Fifty Riyāḍ al-Ṣāliḥīn Aḥmad's Zuhd Suyūṭī
quran:7:142 –

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."  

And We appointed (read wa-wā‘adnā or wa-wa‘adnā) 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 Dhū’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 Dhū’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‘īna 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.
القرآن:٧:١٤٢ –

وَوَاعَدْنَا مُوسَىٰ ثَلَاثِينَ لَيْلَةً وَأَتْمَمْنَاهَا بِعَشْرٍ فَتَمَّ مِيقَاتُ رَبِّهِ أَرْبَعِينَ لَيْلَةً ۚ وَقَالَ مُوسَىٰ لِأَخِيهِ هَارُونَ اخْلُفْنِي فِي قَوْمِي وَأَصْلِحْ وَلَا تَتَّبِعْ سَبِيلَ الْمُفْسِدِينَ  

{وواعدنا} بألف ودونها {موسى ثلاثين ليلة} نكلمه عند انتهائها بأن يصومها، وهي ذو القعدة فصامها فلما تمَّت أنكر خلوف فمه فاستاك فأمره الله بعشرة أخرى ليكلمه بخلوف فمه كما قال تعالى: {وأتممناها بعشر} من ذي الحجة {فتم ميقات ربِّه} وقت وعده بكلامه إياه {أربعين} حال {ليلة} تتميز {وقال موسى لأخيه هارون} عند ذهابه إلى الجبل للمناجاة {اخلفني} كن خليفتي {في قومي وأصلح} أمرهم {ولا تتبع سبيل المفسدين} بموافقتهم على المعاصي.