Sahih Muslim Book 16, Hadith Number 4171.

Chapter : Blood-wit of the child in the womb; and the essentiality of blood-with in case of unintentional murder and in case of the quasi-intentional murder.

Al-Mughira b. Shu’ba reported: A woman killed her fellow-wife with a tent-pole. Her case was brought to Allah’s Messenger (may peace be upon him), and he gave judgment that blood-wit should be paid by the relatives (of the offender) on the father’s side. And as she was pregnant, he decided regarding her unborn child that a male or a female slave of good quality be given. Some of her offender’s) relatives said: Should we make compensation for one who never ate, nor drank, nor made any noise, who was like a nonentity? Thereupon Allah’s Messenger (may peace be upon him) said: He was talking rhymed phrases like the rhymed phrases of desert Arabs.