Abu Dawud Book 34, Hadith Number 4553.
Chapter : Bloodwit for an unborn child.
Narated By N/A : Al-Miswar b. Makhramah said: ‘Umar consulted the people about the compensation for Aburtion of a woman. Al-Mugbirah b. Shu’bah said: I was present with the Apostle of Allah (may peace be upon him) when he gave judgment that a male or a female slave should be paid in compensation for it. He said: Bring another man with you who should testify you. So he brought Muhammad b. Maslamah to him. Harun added: He then testified him.
Imlas means a man striking the belly of his wife.
Abu Dawud said: I have been informed that Abu ‘Ubaid said : It (Abortion) is called imlas because the woman causes it to slip before the time of delivery. Similarly, anything which slips from the hand or from some other thing is called malasa (slipped).