Tafsir of Al-A'raf 7:153

{And those who committed evil deeds}—meaning disbelief and all acts of disobedience—{then repented}—meaning they returned {thereafter}—to Allah and sought His pardon—{and believed}—and made their faith sincere.

{Indeed, your Lord, thereafter}—after those grave sins—{is Forgiving}—a concealer of their faults and an eraser of what they committed—{Merciful}—bestowing upon them the blessing of Paradise.

This is a general ruling that encompasses those who took the calf and everyone else, regardless of whether their crime was grave or otherwise. He magnified the gravity of their offense, then followed it with the magnification of His mercy, so that it may be known that even if sins are great and momentous, His pardon and generosity are greater and more momentous.

However, the condition must be upheld: the necessity of repentance and turning back to Him. Anything beyond that is empty greed and a cold delusion to which no prudent person pays any heed.

{And when the anger subsided in Moses, he took up the tablets; and in their inscription was guidance and mercy for those who fear their Lord.}