Surah Al Baqarah Tafseer

And (remember) when We appointed for Musa (Moses) forty nights, and (in his absence) you took the calf (for worship), and you were Zalimun (polytheists and wrongdoers). Then after that We forgave you so that you might be grateful.

Allah said, "Remember My favor on you when I forgave you for worshipping the calf."

This happened after Musa went to the meeting place with his Lord at the end of that period which was forty days. These forty days were mentioned in Surah Al-A`raf, when Allah said,

وَوَعَدْنَا مُوسَى ثَلَـثِينَ لَيْلَةً وَأَتْمَمْنَاهَا بِعَشْرٍ

And We appointed for Musa thirty nights and added (to the period) ten (more). (7:142)

It was said that these days were during the month of Dhul-Qa`dah plus the first ten days in Dhul-Hijjah, after the Children of Israel were delivered from Fir`awn and they safely crossed the sea.

Allah's statement