And We made an appointment with Moses for thirty nights and perfected (7:142)

Almuntakhab Fi Tafsir Alquran Alkarim

Then We ordained the divine assignation for Mussa and arranged the place and the time when We would be exposed to his mental view after he had completed the exclusive religious devotion imposed on him for thirty nights complemented by ten more nights to total forty nights, the requisite for granting him an audience. And when the set time was fulfilled and Mussa was ready to have spiritual audience of Allah, his Creator, he said to his brother Harun: Take my place and act for me among my people and improve the state of things and put an end to abuse, disorder and malpractice and do not yield to those who are characterized by acts of prepensed malice

Tafseer Tafheem-ul-Quran by Syed Abu-al-A'la Maududi

(7:142) And We appointed for Moses thirty nights, to which We added ten, whereby the term of forty nights set by his Lord was fulfilled. *99 And Moses said to Aaron, his brother: 'Take my place among my people, act righteously, and do not follow the path of those who create mischief.' *100

And We made an appointment with Moses for thirty nights and perfected meaning

*99). After the exodus of the Israelites from Egypt which marks, on the one hand, the end of the constraints of slavery and on the other, the beginning of their life as an independent nation, Moses was summoned by God to Mount Sinai in order that he might receive the Law for Israel. He was initially summoned for a period of forty days so that he might single-mindedly devote himself to worshipping, fasting, meditation and reflection and thus develop the ability to receive the revelation which was to put a very heavy burden upon him.
In compliance with God's command, Moses left the Israelites at the place now known as the Wadi al-Shaykh which lies between Nabi Salih and Mount Sinai. The place where the Israelites had camped is presently called
Maydan al-Rahah. At one end of the valley is a hillock where, according to local tradition, the Prophet Salih pitched his tent after his migration from the land of Thamud. A mosque built as a monument to the Prophet Salih still adorns the landscape. Mount Harun is located at the other end of the valley where, again, according to local tradition, the Prophet Harun (Aaron) stayed after his exasperation with the Israelites because of their cow-worship. The top of the towering Mount Sinai, standing 7,359 feet high, is mostly enveloped by clouds. The cave to which Moses retired for forty days to devote himself to worship and meditation is situated at the top of the mountain, and still attracts many pilgrims. Close to the cave are a mosque and a church. Moreover, a monastery built in the Justinian period stands even today at the foot of the mountain. (See Tafhim al-Qur'an, al-Naml 27: nn. 9-10.)
*100). Although Aaron was senior to Moses in age by three years, he was placed under the direction of the Prophet Moses and was required to assist him in connection with his mission, As explained elsewhere in the Qur'an, Aaron was not assigned independent prophethood; he was rather appointed a Prophet by God in response to Moses' prayer that he be appointed as his assistant. (See Ta Ha 20: 29-31 - Ed.)
 

And We made an appointment with Moses for thirty nights and perfected meaning in Urdu

ہم نے موسیٰؑ کو تیس شب و روز کے لیے (کوہ سینا پر) طلب کیا اور بعد میں دس دن کا اور اضافہ کر دیا، اِس طرح اُس کے رب کی مقرر کردہ مدت پورے چالیس دن ہو گئی موسیٰؑ نے چلتے ہوئے اپنے بھائی ہارونؑ سے کہا کہ "میرے پیچھے تم میری قوم میں میری جانشینی کرنا اور ٹھیک کام کرتے رہنا اور بگاڑ پیدا کرنے والوں کے طریقے پر نہ چلنا"