Qurbani (sacrifice) which is performed as oath (Wajib Zazar) ie he promises with Allah swt that if a ill person granted Shafa, Allah swt recovers him from illness he will sacrifice a sheep or caw.
Holy Prophet sws has sacrificed 120 camels, the reason behind Qurbani is that a person refrains from dependence of worldly things, he demonstrates that I would give up from his belonging for the sake of command of Allah swt and that Allah swt is real owner and he does not own anything, shows submission to Allah swt and high quality of the morality.