أَلَمْ يَعِدْكُمْ رَبُّكُمْ وَعْدًا حَسَنًا (Did your Lord not promise you a good promise? - 20:86) Sayyidna Musa (علیہ السلام) returned to his people full of sorrow and anger. First of all he reminded them of the promise which Allah had made to them that He would give them a Book for their guidance by adhering to which they could achieve all their worldly and religious objectives. He said that it was for the purpose of receiving the Book that he had started out with them for the mount of Tur.
أَفَطَالَ عَلَيْكُمُ الْعَهْدُ (Did then the time become too long for you? - 20:86) Not much time had elapsed on Allah's promise and it is inconceivable that the Bani Isra'il could have forgotten it, or if they remembered it, there was no reason for them to despair of its fulfillment on account of delay, thus providing for themselves justification for the worship of the calf.
أَمْ أَرَدتُّمْ أَن يَحِلَّ عَلَيْكُمْ غَضَبٌ مِّن رَّبِّكُمْ (Or did you wish that wrath from your Lord befalls you? - 20:86) But since neither of the two eventualities mentioned above could be contemplated, the only conclusion was that they knowingly and of their own choice invited the wrath of Allah.