Commentary
Sayyidna Musa (علیہ السلام) and the Bani Isra'il, having escaped the Pharaoh's wrath and having crossed the river in safety, proceeded on their journey. Soon they came upon a people who worshipped idols. They said to Sayyidna Musa "These people have adopted the idols as their gods who are visible as well as tangible. Do give us also a god whom we can see and touch.", Sayyidna Musa علیہ السلام replied,إِنَّكُمْ قَوْمٌ تَجْهَلُونَ ﴿138﴾ إِنَّ هَـٰؤُلَاءِ مُتَبَّرٌ مَّا هُمْ فِيهِ وَبَاطِلٌ مَّا كَانُوا يَعْمَلُونَ ﴿139﴾ ("You are really an ignorant people. at these people are in, is sure to be destroyed; and false is what they are doing." - 7:138-139.)
It was then that Allah commanded Sayyidna Musa (علیہ السلام) to bring his people to the mount of Tur where he would receive the Book Torah which would be a code and a policy document for all of them. However, he would have to prepare himself to receive the Torah by observing a fast for thirty days and thirty nights continuously. This period was later extended by a further ten days so that the total period of fasting was forty days and forty nights. Then Sayyidna Musa (علیہ السلام) led his people towards the mount of Tur, but in his eagerness to receive the Torah he hastened ahead so that he could complete his prayers and fasts for the prescribed period of thirty days as early as possible. He appointed Sayyidna Harun (علیہ السلام) to be his deputy during his absence. The Bani Isra'il continued the journey at their leisurely pace while he pushed on hoping that they would join him in due course near the mount of Tur. In the meanwhile Samiri, by his wiles, seduced them into adopting the calf as the object of their worship and thus divided them into three factions. This unfortunate development seriously impeded their progress towards the Tur.
Allah questioned Sayyidna Musa (علیہ السلام) about his haste and the wisdom behind the question
When Sayyidna Musa (علیہ السلام) appeared before Divine Presence, Allah questioned him as to why he had hastened ahead of his people. The obvious purpose of the question was to inform Sayyidna Musa (علیہ السلام) of the mischief into which his people had fallen while he himself, unaware of what had happened in his absence, was expecting their arrival at the Tur (Ibn Kathir). On the other hand, according to Ruh ul-Maani, the question contained an implied rebuke to Sayyidna Musa (علیہ السلام) on his haste which deprived his people of his supervision and enabled Samiri to mislead them. His position as a prophet made it incumbent on him to stay with his people and keep a watchful eye on them and their activities. The learned commentator has further observed that this question implied an indication that a leader should remain behind his people when travelling with them, as Allah Ta` ala had ordered but to bring his people out of the city and to remain at their back وَاتَّبِعْ أَدْبَارَهُمْ (follow them at the rear -15:65)
Sayyidna Musa (علیہ السلام) ، ignorant of Samiri's mischief, answered the question put to him by Allah that his haste was the result of his ardent desire to fulfill Allah's command without loss of time so as to deserve His greater favour, and that his people were close behind him and might arrive at any time. It was at that moment that Allah informed him of the evil that had befallen his people and the part played by Samiri in bringing it about.