﴿ وَإِذْ وَٰعَدْنَا مُوسَىٰٓ أَرْبَعِينَ لَيْلَةًۭ ثُمَّ ٱتَّخَذْتُمُ ٱلْعِجْلَ مِنۢ بَعْدِهِۦ وَأَنتُمْ ظَٰلِمُونَ ﴾

“and when We appointed for Moses forty nights [on Mount Sinai], and in his absence you took to worshipping the [golden] calf, and thus became evildoers:”

Please check ayah 2:53 for complete tafsir.