And [recall] when Moses said to his people, "O my people, indeed (2:54)

﴿وَإِذْ قَالَ مُوسَىٰ لِقَوْمِهِ يَا قَوْمِ إِنَّكُمْ ظَلَمْتُمْ أَنفُسَكُم بِاتِّخَاذِكُمُ الْعِجْلَ فَتُوبُوا إِلَىٰ بَارِئِكُمْ فَاقْتُلُوا أَنفُسَكُمْ ذَٰلِكُمْ خَيْرٌ لَّكُمْ عِندَ بَارِئِكُمْ فَتَابَ عَلَيْكُمْ ۚ إِنَّهُ هُوَ التَّوَّابُ الرَّحِيمُ﴾
[ البقرة: 54]

2:54 And [recall] when Moses said to his people, "O my people, indeed you have wronged yourselves by your taking of the calf [for worship]. So repent to your Creator and kill yourselves. That is best for [all of] you in the sight of your Creator." Then He accepted your repentance; indeed, He is the Accepting of repentance, the Merciful.

Also, remember that Allah’s allowing you to ask His forgiveness for worshipping the calf, when Moses ( peace be upon him ) told you that you had wronged yourselves by taking the calf as a god and worshipping it, were from the blessings of Allah.
Moses told you to ask for forgiveness and repent to your Creator by some of you killing others, because turning to Him in this way was better for you than persisting in disbelief, which would lead to an eternity in the fire of Hell.
So, you did this with Allah’s approval, and He forgave you, for He is Forgiving and Merciful with His servants.

And (remember) when Musa (Moses) said to his people: "O my people! Verily, you have wronged yourselves by worshipping the calf. So turn in repentance to your Creator and kill yourselves (the innocent kill the wrongdoers among you), that will be better for you with your Lord." Then He accepted your repentance. Truly, He is the One Who accepts repentance, the Most Merciful.

phonetic Transliteration

Waith qala moosa liqawmihi ya qawmi innakum thalamtum anfusakum biittikhathikumu alAAijla fatooboo ila bariikum faoqtuloo anfusakum thalikum khayrun lakum AAinda bariikum fataba AAalaykum innahu huwa alttawwabu alrraheemu

Abdullah Yusuf Ali - Translation

And remember Moses said to his people: "O my people! Ye have indeed wronged yourselves by your worship of the calf: So turn (in repentance) to your Maker, and slay yourselves (the wrong-doers); that will be better for you in the sight of your Maker." Then He turned towards you (in forgiveness): For He is Oft-Returning, Most Merciful.

Safi-ur-Rahman al-Mubarakpuri

And (remember) when Musa said to his people: "O my people! Verily, you have wronged yourselves by worshipping the calf. So turn in repentance to your Creator and kill yourselves (the innocent kill the wrongdoers among you), that will be better for you with your Creator." Then He accepted your repentance. Truly, He is the One Who accepts repentance, the Most Merciful.

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