Musa fasts and worships Allah for Forty Days

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,

يبَنِى إِسْرَءِيلَ قَدْ أَنجَيْنَـكُمْ مِّنْ عَدُوِّكُمْ وَوَاعَدْنَـكُمْ جَانِبَ الطُّورِ الاٌّيْمَنَ

This verse speaks of the period followed by the destruction of the Pharaoh and his people. Having a peaceful time after their deliverance from the Pharaoh and his people the Israelites requested the Prophet Musa (علیہ السلام) to have some religious system of law so that they may act upon it. The Prophet Musa (علیہ السلام) prayed Allah for a code of guidance for them. The Arabic word: واعدنا "wa` adana' is a derivative of وعدہ ; wa` dah' which signifies a worded expression of offering something good to someone - a promise.

Allah made a promise to Musa (علیہ السلام) to send His word to him. It was stipulated that Musa (علیہ السلام) should go to the mount of Sinai and pass thirty nights there sitting in devotion for Allah. These thirty nights were later supplemented with ten more nights to make them forty.