Answer:
So that they hit the dead man with a part of the cow, and he rose from the dead and pointed at his killer. Allah the Almighty says: (So We said: “Strike him (the dead man) with a piece 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.) [Al-Baqarah 2: 73]
There was a wealthy man who had no sons, and his only heir was his nephew. The nephew killed his uncle so he can get the inheritance, and threw his body at someone’s door claiming that that person killed him. People got together and were about to start a fight when someone suggested they ask Moses PBUH what they should do. Moses replied that Allah Almighty commands them to kill a cow. After a lot of questions about the description of the cow, they finally found the cow and slaughtered it and Allah commanded them to hit the dead man with a part of the cow and he will come alive and point at his killer.
:كي يضربوا الميت بجزء من البقرة فيحيا و يدلهم الميت على قاتله. قال الله تعالى
(كَذَٰلِكَ يُحْىِ ٱللَّهُ ٱلْمَوْتَىٰ وَيُرِيكُمْ ءَايَـٰتِهِۦ لَعَلَّكُمْ تَعْقِلُونَ)
كَانَ فِي بَني إِسْرَائِيلَ رَجُلٌ كَثِيرُ المَالِ وَلاَ وَلَدَ لَهُ، وَكَانَ وَارِثَهُ الَوحِيدَ ابْنُ أَخِيهِ، فَاسْتَعْجَلَ ابْنُ الأَخِ المِيرَاثَ. وَقَتَلَ عَمَّهُ، ثُمَّ حَمَلَهُ وَأَلْقَاهُ عَلَى بَابِ رَجُل مِنْهُمْ. وَادَّعَى عَلَى صَاحِبِ البَيْتِ أَنَّهُ قَاتِلُهُ، وَتَسَلَّحَ النَّاسُ، وَتَثَاوَرُوا حَتَّى كَادَ الشَّرُّ أَنْ يَقَعَ بَيْنَهُمْ. فَدَعَاهُمْ ذَوُو الرَّأْيِ فِيهِمْ أَنْ يَذْهَبُوا إِلى مُوسَى يَسْأَلُونَهُ الرَّأْيَ، فَقَالَ لَهُمْ مُوسَى: إِنَّ اللهَ يَأْمُرُكُمْ أَنْ تَذْبَحُوا بَقَرَةً . و بعدأن صف لهم البقرة, اشتروها. فَأَمَرَهُمُ اللهُ تَعَالَى بِضَرْبِ المَيْتِ بِأَيِّ جُزْءٍ مِنْ أَجْزَاءِ البَقَرَةِ التِي أَمَرَهُمُ اللهُ بِذَبْحِهَا فَفَعَلُوا، وَحَصَلَتِ المُعْجِزَةُ بِخَرْقِ العَادَةِ، فَأَحْيَا اللهُ المَيْتَ، وَذَكَرَ اسْمَ قَاتِلِهِ، ثُمَّ أَمَاتَهُ اللهُ فَسَكَنَتِ الفِتْنَةُ، بَعْدَ أَنْ كَشَفَ اللهُ القَاتِلَ. وَهَكَذَا يُحْيِي اللهُ المَوْتَى،