Narrated One of Ansar:
Sulayman ibn Yasar, the freed slave of Maymunah, the wife of Allah's Apostle (peace_be_upon_him), narrated from one of the Ansari Companions of Allah's Messenger (may pace be upon him) that Allah's Messenger (peace_be_upon_him) retained (the practice) of Qasamah as it was in the pre-Islamic days.
Narrated Wa'il ibn Hujr:
While I was sitting in the company of Allah's Apostle (peace_be_upon_him), a person came there dragging another one with the help of a strap and said: Allah's Messenger, this man has killed my brother. Allah's Messenger (peace_be_upon_him) said to him: Did you kill him? And the other man said: (In case he did not make a confession of this, I shall bring a witness against him). He (the murderer) said: Yes, I killed him. He (the Holy Prophet) said: Why did you kill him? He said: He and I were striking down the leaves of a tree and he abused me and enraged me, so I struck his head with an axe and killed him. Thereupon Allah's Messenger (peace_be_upon_him) said: Have you anything with you to pay blood-money on your behalf? He said: I do not possess any property but this robe of mine and this axe of mine. He (the Holy Prophet) said: Do you think your people will pay ransom for you? He said: I am more insignificant among my people than this (that I would not be able to obtain this benefit from my tribe). He (the Holy Prophet) threw the strap towards him (the claimant of the blood-money) saying: Take away your man.
The man took him away, and as he returned, Allah's Messenger (peace_be_upon_him) said: If he kills him, he will be like him. He returned and said: Allah's Messenger, it has reached me that you said that "If he killed him, he would be like him." I caught hold of him according to your command. Thereupon Allah's Messenger (peace_be_upon_him) said: Don't you want him to take upon himself (the burden) of your sin and the sin of your companion (your brother)? He said: Allah's Apostle, why not? The Messenger of Allah (peace_be_upon_him) said: If it is so, then let it be. He threw away the strap (around the offender) and set him free.
Narrated Al-Mughirah ibn Shu'bah:
A woman struck her co-wife with a tent-pole and she was pregnant and she killed her. One of them belonged to the tribe of Lihyan. Allah's Messenger (peace_be_upon_him) made the relatives of the murderer responsible for the payment of blood-wit on her behalf, and fixed a slave or a female slave as the indemnity for what was in her womb.
One of the persons amongst the relatives of the murderer said: Should we pay indemnity for one who neither ate, nor drank, nor made any noise, who was just like a nonentity? Thereupon Allah's Messenger (peace_be_upon_him) remarked: He speaks rhymed phrases like the people of the desert. He did impose indemnity upon them.