It is narrated from Abdullah bin Amr bin Al-As (may Allah be pleased with him) that the Messenger of Allah (ﷺ) said: "Whoever kills a sparrow or anything smaller than that without a just cause, Allah will question him about its killing." It was asked: "O Messenger of Allah (ﷺ)! What is its right?" He (ﷺ) said: "That he should slaughter it and then eat it, and not cut off its head and then use it for target practice."
Hadith Referenceمسند الإمام الشافعي / كتاب القتل والقصاص والديات والقسامة / 1615
Ikrimah (may Allah have mercy on him) narrated that when Ibn Abbas (may Allah be pleased with them both) received the news that Ali (may Allah be pleased with him) had burned apostates and irreligious people, he said: "If I had been in his place, I would not have burned them; rather, I would have killed them, because the Messenger of Allah (ﷺ) said: 'Whoever changes his religion (Islam), kill him.' And I would not have burned them because the Messenger of Allah (ﷺ) said: 'It is not permissible for anyone to punish with Allah's punishment.'"
Hadith Referenceمسند الإمام الشافعي / كتاب القتل والقصاص والديات والقسامة / 1616
Ja'far bin Muhammad narrated from his father that Ali (may Allah be pleased with him) said regarding Ibn Muljam when he wounded him: "Feed him, give him drink, and keep him imprisoned in a good manner. If I survive, I am the guardian of my own blood; if I wish, I will forgive him, and if I wish, I will take retribution. And if I am martyred, then kill him, but do not mutilate him."
Hadith Referenceمسند الإمام الشافعي / كتاب القتل والقصاص والديات والقسامة / 1617
Hadith Takhrijاسناده ضعيف لضعف شيخ الشافعي ولإنقطاعه بين محمد بن علی و علی بن ابی طالب: اخرجه البیهقی: 8/ 183 - وفي المعرفة السنن والآثار له (5003)۔