On the authority of Abdullah, from the Prophet ﷺ, who said: "No soul is killed unjustly but that the first son of Adam bears a share of its blood, because he was the first to set the precedent of killing."(1)

2 - Chapter: The Severity of Shedding Blood

3986 - Muhammad ibn Mu'awiyah ibn Malik informed us, saying: Muhammad ibn Salamah al-Harrani narrated to us, from Ibn Ishaq, from Ibrahim ibn Muhajir, from Isma'il, the freed slave of Abdullah ibn Amr ibn al-As, from Abdullah ibn Amr ibn al-As, who said: The Messenger of Allah ﷺ said: "By Him in Whose hand is my soul, the killing of a believer is greater before Allah than the passing away of the entire world."(3) Abu Abd al-Rahman said: Ibrahim ibn al-Muhajir is not strong (in hadith).

--------------------------------------------
(1) Its chain is authentic. Abd al-Rahman: he is Ibn Mahdi, and Sufyan: he is Ibn Sa'id al-Thawri, and al-A'mash: he is Sulayman ibn Mihran, and Masruq: he is Ibn al-Ajda'. It is in "Al-Sunan al-Kubra" under number (3433).
It was also narrated by Ahmad (4092) and (4123), al-Bukhari (6867), and al-Tirmidhi (2673) via chains from Sufyan al-Thawri, with this chain. Al-Bukhari's narration is abridged.
It was also narrated by Ahmad (3630), al-Bukhari (3335) and (7321), Muslim (1677), the compiler in "Al-Kubra" (11077), Ibn Majah (2616), and Ibn Hibban (5983) via chains from al-A'mash, with it.
Al-Sindi said: His saying "the first" means: the one who was the first killer, not the first of offspring. "Kifl" — with a kasrah on the kaf — is the portion and share. "The first to set the precedent of killing" — so he is followed in this act, and the one who sets the precedent has a share of the act of those who follow him, even if the follower did not intend to follow him in the act. And Allah knows best.
(2) It was corrupted in (R) and (M) to: Salih.
(3) A hadith that may be considered hasan (good), but this chain is weak, containing more than one defect: Ibn Ishaq — who is Muhammad — is a mudallis (one who conceals), and he used 'an'anah (ambiguous transmission) in it, and Ibrahim ibn al-Muhajir is not strong as the compiler stated after it, and Isma'il, the freed slave of Abdullah ibn Amr — who is al-Sahmi — is unknown, and only Ibrahim ibn [al-Muhajir] narrated from him.