Musnad Ahmad 28:237

'Abd al-Razzaq narrated to us, Dawud ibn Qays informed us, from 'Amr ibn Shu'ayb, from his father, from his grandfather, who said: The Messenger of Allah (peace and blessings of Allah be upon him) was asked about the *'aqiqah* (slaughtering for a newborn). He said: "Indeed, Allah does not love *'uquq* (disobedience/undutifulness)," as if he disliked the name. They said: "O Messenger of Allah, we are only asking you about one of us who has a child born to him?" He said: "Whoever among you likes to perform a sacrifice (*nusuk*) for his child, let him do so. For the boy, two equivalent sheep, and for the girl, one sheep." He said: And he was asked about the *far'* (the firstborn of a camel/sheep offered to idols). He said: "The *far'* is a right, but that you leave it until it becomes strong or a young camel (*ibn makhad* or *ibn labun*), then you carry upon it in the way of Allah, or give it to a widow, is better than that you slaughter it, its meat sticking to its fur, and you overturn your vessel, and deprive your she-camel of its young." And he said: And he was asked about the *'atirah* (sacrifice in the month of Rajab). He said: "The *'atirah* is a right." Some of the people said to 'Amr ibn Shu'ayb: "What is the *'atirah*?" He said: "They used to slaughter a sheep in Rajab, then they would cook it, eat it, and feed others."