The first question of Fatwa no. 7465
Q 1: What is the ruling on sacrificing an animal at a specific date and time every year? Many people believe that slaughtering on the 27th of Rajab, 6th of Safar, 15th of Shawwal and 10th of Muharram draw them close to Allah and is an act of ‘Ibadah (worship). Are these acts valid? Are they acts of Sunnah or Bid‘ah (innovation in religion) that contradicts Islam and its doer will not be rewarded for them?
A: All acts of ‘Ibadah that draw a Muslim close to Allah are Tawqifiy (bound by a religious text and not amenable to personal opinion).
There is no textual proof from the Qur’an or the authentic Sunnah that dictate a particular sacrifice on the mentioned days of these months. The Sahabah (Companions of the Prophet – may Allah be pleased with them) did not do so either and therefore, this is Bid‘ah. It is authentically reported that the Prophet (peace be upon him) said: Anyone who introduces anything into this matter of ours (Islam) that is not part of it will have it rejected. (Related by Al-Bukhari and Muslim)
May Allah grant us success! May peace and blessings be upon our Prophet Muhammad, his family, and Companions!
source : http://alifta.com