Sahih Bukhari | Volume 7 | Hadith Number 380

Narrated by Salman bin 'Amir Ad-Dabbi
I heard Allah's Apostle saying, "'Aqiqa is to be offered for a (newly born) boy, so slaughter (an animal) for him, and relieve him of his suffering." (Note: It has been quoted in Fateh-AL-Bari that the majority of the Religious Scholars agrees to the Hadith narrated in Sahih At-Tirmidi that the Prophet was asked about Aqiqa and he ordered 2 sheep for a boy and one sheep for a girl and that is his tradition "SUNNA".)