Jami` at-Tirmidhi 1512
جامع الترمذي#1512SahihNarrated Abu Hurairah:That the Messenger of Allah (ﷺ) said: "There is no Fara' or 'Atirah." The Fara' is the first of the offspring that would be born to them, so they would slaughter it. The 'Atirah was an animal that they would slaughter during Rajab to honor the month of Rajab, since it was the first of the sacred months
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Ahmad Muhammad ShakirSahih
Al-AlbaniSahih
Bashar Awad MaaroufHasan Sahih
Zubair Ali ZaiSahih - Agreed Upon
In-book reference: 19:23