And remember We appointed forty nights for Moses, and in his absence ye took the calf (for worship), and ye did grievous wrong.
According to Abdullah Yusuf Ali,
C66. This was after the Ten Commandments and the
Laws and Ordinances had been given on Mount Sinai:
Moses was asked up into the Mount, and he was there
forty days and forty nights: Exod. 24:18.
But the people got impatient of the delay, made a calf of
melted gold, and offered worship and sacrifice to it:
Yusuf Ali, Abdullah. Translation and Commentary of the Quran. (Surah 2 verse 51). Microsoft Word – 002 Baqarah.doc (quran4u.com)