Abu Dawud Book 34, Hadith Number 4483.

Chapter : If authorities ask relatives of a slain to forgo their right what should they do.

Narated By Abu Hurayrah : A man was killed in the lifetime of the Prophet (PBUH). The matter was brought to the Prophet (PBUH). He entrusted him to the legal guardian of the slain. The slayer said: Apostle of Allah, I swear by Allah, I did not intend to kill him. The Apostle of Allah (PBUH) said to the legal guardian: Now if he is true and you kill him, you will enter Hell-fire. So he let him go. His hands were tied with a strap. He came out pulling his strap. Hence he was called Dhu an-Nis’ah (possessor of strap).