In The Name of Allaah, The Most Merciful, The Bestower of Mercy.
Ataa [rahimahullaah] narrated, “A woman said in the presence of Aa’isha, ‘If the wife of such and such gives birth, we’ll slaughter a camel’. So, Aa’isha said, ‘But the Sunnah is that two sheep are to be slaughter for the birth of a boy and one sheep for the birth of a girl’”.
Shaikh Zaid said, “In this hadeeth there’s evidence that Ghuluww [going beyond what the Shar’ee’ah has legislated- neither commanded nor recommended] is forbidden, and that adherence to the Sunnah is the truth. If a newly born child is a boy, then his guardian [i.e. father] should slaughter two sheep; and if the child is a girl, one sheep is slaughtered for her. One should not obligate on himself to slaughter a camel, for indeed he has not been commanded to do that. Limiting oneself to the Sunnah is the good thing to do instead of encroaching its legislated boundaries.
[At-taleeqaat Al-Maleehah Alaa Silsilah al-Ahaadeeth As-Saheeh. Vol 1. Page 416]