Sahih al-Bukhari, Volume 7, Book 66, Hadith 383 (USC-MSA) ⓘ

Narrated Abu Huraira: The Prophet said, "Neither Fara' nor 'Atira) is permissible)." Al-Fara' was the first offspring (they got of camels or sheep) which they (pagans) used to offer (as a sacrifice) to their idols. 'Atira was (a sheep which used to be slaughtered) during the month of Rajab.

حَدَّثَنَا عَلِيُّ بْنُ عَبْدِ اللَّهِ، حَدَّثَنَا سُفْيَانُ، قَالَ الزُّهْرِيُّ حَدَّثَنَا عَنْ سَعِيدِ بْنِ الْمُسَيَّبِ، عَنْ أَبِي هُرَيْرَةَ، عَنِ النَّبِيِّ صلى الله عليه وسلم قَالَ ‏ "‏ لاَ فَرَعَ وَلاَ عَتِيرَةَ ‏" ‏‏.‏ قَالَ وَالْفَرَعَ أَوَّلُ نِتَاجٍ كَانَ يُنْتَجُ لَهُمْ، كَانُوا يَذْبَحُونَهُ لِطَوَاغِيتِهِمْ، وَالْعَتِيرَةُ فِي رَجَبٍ‏.‏