From Sahih Bukhari (Hadith 3828):
Narrated Asma bint Abi Bakr:I saw Zaid bin Amr bin Nufail standing with his back against the Ka'ba and saying, "O people of Quraish! By Allah, none amongst you is on the religion of Abraham except me." He used to preserve the lives of little girls: If somebody wanted to kill his daughter he would say to him, "Do not kill her for I will feed her on your behalf." So he would take her, and when she grew up nicely, he would say to her father, "Now if you want her, I will give her to you, and if you wish, I will feed her on your behalf
Reference: Bukhari 3828