It was narrated that Anas bin Malik said:
"A man brought the killer of his relative to the Messenger of Allah (ﷺ) and the Messenger of Allah (ﷺ) said: 'Pardon him,' but the refused. He said: 'Take the blood money,' but he refused. He said: 'Go and kill him, but then you will be like him.' Someone caught up with him and reminded him that the Messenger of Allah (ﷺ) had said: 'Go and kill him, but then you will be like him.' So he let him go. (ES)
English reference (ES): Vol. 3, Book 21, Hadith 2691 (ES)
Arabic reference (ES): Book 21, Hadith 2793 (ES)