Surah Al-Baqarah — Ayah 51 (2:51)
وَإِذۡ وَٰعَدۡنَا مُوسَىٰٓ أَرۡبَعِينَ لَيۡلَةٗ ثُمَّ ٱتَّخَذۡتُمُ ٱلۡعِجۡلَ مِنۢ بَعۡدِهِۦ وَأَنتُمۡ ظَٰلِمُونَ ٥١
English translation (Saheeh International)
And [recall] when We made an appointment with Moses for forty nights. Then you took [for worship] the calf after him [i.e., his departure], while you were wrongdoers.
Brief commentary
Also, remember that the forty nights appointed to Moses were from the blessings of Allah, in which the revelation of the Torah, with its light and guidance, was completed. Yet you went and worshipped the calf during that period, which made you into wrongdoers.