Allah the Almighty narrated: And (remember) when Moses said to his people: "Verily, Allah commands you that you slaughter a cow.
They said: "Do you make fun of us?"
He said: "I take Allah's Refuge from being among AlJahileen (the ignorants or the foolish)."
They said: "Call upon your Lord for us that He may make plain to us what it is!"
He said: "He says, 'Verily, it is a cow neither too old nor too young, but (it is) between the two conditions; so do what you are commanded."
They said: "Call upon your Lord for us to make plain to us its color."
He said: "He says, 'It is a yellow cow bright in its color, pleasing to the beholders.
They said: "Call upon your Lord for us to make plain to us what it is. Verily to us all cows are alike, and surely, if Allah wills, we will be guided."
He (Moses) said: "He says, 'It is a cow neither trained to till the soil nor water the fields, sound, having no other color except bright yellow.
They said: "Now you have brought the truth." So they slaughtered it though they were near to not doing it.
And (remember) when you killed a man and fell into dispute among yourselves as to the crime. But Allah brought forth that which you were hiding. So We said: "Strike him (the dead man) with apiece of it (the cow)." Thus Allah brings the dead to life and shows you His Ayat (proofs, evidences, verses, lessons, signs, revelations, etc.) so that you may understand.
Then after that your hearts were hardened and became as stones or even worse in hardness. And indeed, there are stones out of which rivers gush forth, and indeed, there are of them (stones) which fall down for fear of Allah. And Allah is not unaware of what you do. Surah 2: 67-74