Sunan Abi Dawud, Hadith 2826

Narrated Sa'id: Fara' was the first animal born to them (the Arabs) which they sacrificed.

حَدَّثَنَا الْحَسَنُ بْنُ عَلِيٍّ، حَدَّثَنَا عَبْدُ الرَّزَّاقِ، أَخْبَرَنَا مَعْمَرٌ، عَنِ الزُّهْرِيِّ، عَنْ سَعِيدٍ، قَالَ الْفَرَعُ أَوَّلُ النِّتَاجِ كَانَ يُنْتَجُ لَهُمْ فَيَذْبَحُونَهُ ‏.‏

sunnah.com

also referenced under: Hadith 2832 (DarusSalam)