Ibn Sa`d’s Kitab al-Tabaqat al-Kabir, Moinul Haq Translation, Vol.2, pages 30-31
Umayr Ibn Adi came to her in the night and entered her house. Her children were sleeping around her. There was one whom she was suckling.
He searched her with his hand because he was blind, and separated the child from her. He thrust his sword in her chest till it pierced up to her back. Then he offered the morning prayers with the prophet
at al-Medina. The apostle of Allah said to him: “Have you slain the daughter of Marwan?” He said: “Yes.
Is there something more
for me to do?” He [Muhammad] said: “No. Two goats will butt together about her
From Sirat Rasul Allah, Guillaume Tranlsation (21st impression,Page 676)
..Muhammad said [ ‘Who will rid me of Marwan’s Daughter?
‘ ‘Umayr b. Adiy al-Khatmi who was with him heard him, and that very night he went to her house and killed her
. In the morning he came to the apostle and told him what he had done and he (Muhammad) said, ‘You have helped God and His apostle
, O ‘Umayr!’ When he asked if he would have to bear any evil consequences
the apostle said, ‘Two goats won’t butt their heads about her
.’ ( Muhammad meant that she was worthless)