Tafsir of Al-Baqarah 2:51

"And [recall] when We appointed a time for Moses..."

When the Children of Israel entered Egypt after the destruction of Pharaoh, and they possessed no scripture to guide them, God promised Moses that He would send down the Torah upon him. He set a time for him: the month of Dhu al-Qa'dah and ten days of Dhu al-Hijjah. It is said:

"Forty nights"

This is because months begin with their nights.

It is also recited as: "We promised" (wa'adna), because God Almighty promised him the revelation and promised his arrival at the appointed time at Mount Sinai.

"After him"

Meaning: after his departure to the Mount.

"While you were wrongdoers"

By your act of polytheism (shirk).

"Then We forgave you"

When you repented.

"After that"

After you committed the grave matter, which was your taking of the Calf.

"That you might be grateful"

Meaning: intending that you should be grateful for the blessing of being forgiven.

"And [recall] when We gave Moses the Scripture and the Criterion that you might be guided. And [recall] when Moses said to his people, 'O my people, indeed you have wronged yourselves by your taking of the Calf; so repent to your Creator and kill yourselves. That is best for you in the sight of your Creator.' Then He accepted your repentance; indeed, He is the Accepting of repentance, the Merciful." (54)