وَإِذْ قَالَ مُوسَى لِقَوْمِهِ إِنَّ اللَّهَ يَأْمُرُكُمْ أَنْ تَذْبَحُوا بَقَرَةً قَالُوا أَتَتَّخِذُنَا هُزُوًا قَالَ أَعُوذُ بِاللَّهِ أَنْ أَكُونَ مِنَ الْجَاهِلِينَ ﴿67﴾ قَالُوا ادْعُ لَنَا رَبَّكَ يُبَيِّنْ لَنَا مَا هِيَ قَالَ إِنَّهُ يَقُولُ إِنَّهَا بَقَرَةٌ لَا فَارِضٌ وَلَا بِكْرٌ عَوَانٌ بَيْنَ ذَلِكَ فَافْعَلُوا مَا تُؤْمَرُونَ ﴿68﴾

﴾67﴿ Wa iz qaala Moosaa liqawmiheee innal laaha yaamurukum an tazbahoo baqaratan qaalooo atattakhizunna huzuwan qaala a'oozu billaahi an akoona minal jaahileen
﴾68﴿ Qaalud-'u lanaa rabbaka yubaiyil lanaa maa hee; qaala innahoo yaqoolu innahaa baqaratul laa faaridunw wa laa bikrun 'awaanum baina zaalika faf'aloo maa tu'maroon

﴾67﴿ And when Moses (peace be upon him) said to his people, “Indeed, Allah commands you to slaughter a cow,” they said, “Do you make a mockery of us?” He (Moses) replied, “I seek refuge in Allah from being among the ignorant.”
﴾68﴿ They said, “Call upon your Lord for us to make clear to us what age this cow should be.” Moses (peace be upon him) said, “Indeed, Allah says: It is a cow neither old nor young, but in between—moderate in age. So do what you are commanded.”

[67] This verse mentions their second corruption: that they would twist the commands of Allah through excuses and delay. The command to slaughter a cow was given because the cow had become an object of worship for the Children of Israel—slaughtering it would prove their commitment to monotheism. However, due to weakness in their faith, they began questioning the command. Ibn al-Qayyim noted in his tafsīr that the connection between the incident of murder and the command to slaughter a cow is based on Israelite narrations. Ibn Kathīr wrote that there was a forty-year gap between both incidents. This verse also indicates that attributing falsehood to Allah is a great act of ignorance—and that the prophets (peace be upon them) are protected from such ignorance.
[68] These were their excuses to delay fulfilling the command—so Allah made the command more difficult for them. Interestingly, the calf they had once worshipped had similar traits. (Lā fāriḍ) – refers to a cow that is not old, whose age has not passed its prime. (Bikr) – refers to a young cow that has not yet borne a calf—not a newly born, but one that hasn’t yet conceived. (ʿAwān) – means one of middle age, between old and young (between fāriḍ and bikr). (Bayna dhālik) – means it is perfectly balanced in age, not leaning toward either extreme.