Hadithcore
Mishkat al-Masabih, 1477

Abu Huraira reported the Prophet (ﷺ) as saying, “There is no <i>fara’</i> and no <i>‘atira</i>.” He said that the <i>fara’</i> was the first animal born to them which they sacrificed to their idols, and the <i>‘atira</i> was observed in Rajab.* * These were practices of the idolatrous pre-Islamic Arabs. While the <i>fara'</i> sacrifice was abolished in Islam, it is said that the sacrifice of a sheep or goat in Rajab, known as the <i>‘atira</i>, was continued in the early days of Islam and then abolished. (Bukhari and Muslim.)

عَنْ أَبِي هُرَيْرَةَ عَنِ النَّبِيِّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ قَالَ: «لَا فَرَعَ وَلَا عَتِيرَةَ» . قَالَ: وَالْفرع: أول نتاج كَانَ ينْتج لَهُمْ كَانُوا يَذْبَحُونَهُ لِطَوَاغِيتِهِمْ. وَالْعَتِيرَةُ: فِي رَجَبٍ

References1 variant
In-Book Reference
Book 4, Hadith 877