Ibn Kathir reports from Ibn Abbas, through Ali ibn Abi Talhah: a crow came to a dead crow and scratched earth over it until it covered it, and the one who had killed his brother said: Alas! Have I even failed to be like this crow and bury the corpse of my brother? As-Suddi reported, with his chain to the Companions, that when the young man died his brother left him in the open, not knowing how to bury him, so Allah sent two crows, brothers, which fought until one killed the other, then dug for it and covered it with earth; when he saw this, he said those words. How the killing came about is explained in how the conflict started between the two sons of Adam.
قَالَ يَا وَيْلَتَا أَعَجَزْتُ أَنْ أَكُونَ مِثْلَ هَٰذَا الْغُرَابِ فَأُوَارِيَ سَوْءَةَ أَخِي (سورة المائدة: 31)

قال ابن كثير: قال علي بن أبي طلحة عن ابن عباس: جاء غراب إلى غراب ميت، فبحث عليه من التراب حتى واراه، فقال الذي قتل أخاه: (يا ويلتا أعجزت أن أكون مثل هذا الغراب فأواري سوءة أخي) (المائدة 5: 31)، وقال السدي بإسناده إلى الصحابة: لما مات الغلام تركه بالعراء، ولا يعلم كيف يدفن، فبعث الله غرابين أخوين، فاقتتلا فقتل أحدهما صاحبه، فحفر له ثم حثى عليه، فلما رآه قال ما قال.

Allah had said of the killer: so he killed him, becoming a loser (5:30), and after the crow: So he became regretful (5:31). Ibn Kathir reports that al-Hasan al-Basri said: Allah covered him with regret after loss. Ibn Kathir notes that the Prophet said: No sin is more deserving of having its punishment hastened by Allah in this world, along with what is stored up for its doer in the Hereafter, than transgression and cutting the ties of kinship (Jami at-Tirmidhi 2511, which at-Tirmidhi graded hasan sahih), and that both were combined in this deed. The story itself is told in Surah Al-Ma’idah, as explained in which surah mentions the two sons of Adam.
فَطَوَّعَتْ لَهُ نَفْسُهُ قَتْلَ أَخِيهِ فَقَتَلَهُ فَأَصْبَحَ مِنَ الْخَاسِرِينَ (سورة المائدة: 30)

قال تعالى في القاتل: (فقتله فأصبح من الخاسرين) (المائدة 5: 30)، وقال بعد ذكر الغراب: (فأصبح من النادمين) (المائدة 5: 31)، قال الحسن البصري: علاه الله بندامة بعد خسران، وذكر ابن كثير قول النبي صلى الله عليه وسلم: "ما من ذنب أجدر أن يعجل الله لصاحبه العقوبة في الدنيا مع ما يدخر له في الآخرة من البغي وقطيعة الرحم" (جامع الترمذي 2511، وقال: حديث حسن صحيح)، ثم قال: وقد اجتمع في فعل قابيل هذا وهذا.

Allah says of the human being: then causes them to die and be buried (80:21). Ibn Kathir explains: He made him one who has a grave. Al-Qurtubi cites al-Farra’: He gave him a grave in which he is hidden, as an honour, and did not make him one of those cast on the face of the earth for birds and wild animals to eat. Allah also says: Have We not made the earth a lodging for the living and the dead? (77:25-26) Ibn Kathir reports Mujahid’s explanation: it holds the dead, so nothing of him is seen; and ash-Sha’bi’s: its inside is for your dead and its surface for your living.
ثُمَّ أَمَاتَهُ فَأَقْبَرَهُ (سورة عبس: 21)

قال تعالى في الإنسان: (ثم أماته فأقبره) (عبس 80: 21)، قال ابن كثير: أي: جعله ذا قبر، وقال القرطبي: أي جعل له قبرا يوارى فيه إكراما، ولم يجعله مما يلقى على وجه الأرض تأكله الطير والعوافي، قاله الفراء، وقال تعالى: (ألم نجعل الأرض كفاتا أحياء وأمواتا) (المرسلات 77: 25-26)، قال مجاهد: يكفت الميت فلا يرى منه شيء، وقال الشعبي: بطنها لأمواتكم، وظهرها لأحيائكم.