﴿ ۞ وَوَٰعَدْنَا مُوسَىٰ ثَلَٰثِينَ لَيْلَةًۭ وَأَتْمَمْنَٰهَا بِعَشْرٍۢ فَتَمَّ مِيقَٰتُ رَبِّهِۦٓ أَرْبَعِينَ لَيْلَةًۭ ۚ وَقَالَ مُوسَىٰ لِأَخِيهِ هَٰرُونَ ٱخْلُفْنِى فِى قَوْمِى وَأَصْلِحْ وَلَا تَتَّبِعْ سَبِيلَ ٱلْمُفْسِدِينَ ﴾

“AND [then] We appointed for Moses thirty nights [on Mount Sinai]; and We added to them ten, whereby the term of forty nights set bye, his Sustainer was fulfilled. And Moses said unto his brother Aaron: "Take thou my place among my people; and act righteously, and follow not the path of the spreaders of corruption."”

Moses was given dawah commands in Egypt, while laws were communicated to him after he reached the Sinai desert. This shows the order of divine injunctions. In general situations, what is required of the believers is to rectify their personal life and live as true devotees of God, and along with this, they must invite others to accept monotheism and the Hereafter-oriented life. But when the believers acquire the position of an independent community and have the freedom to organize themselves as the Israelites did in the Sinai desert, then it becomes incumbent on them to establish their social life on the basis of the Islamic law. When Moses appointed Aaron as guardian of the Israelites in his absence, he said to him, ‘Take my place among my people: act rightly and do not follow the way of those who spread corruption.’ This shows the basic principle of shouldering one’s responsibilities as the head of the community.