What is the basis for offering the Eid prayer the next day if confirmation of the day occurs after sunset?

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The prayer is offered the next day if confirmation occurs after sunset because the Eid of the next day is established by the saying of the Prophet, peace be upon him: "Your breaking of the fast (Fitr) is the day you break the fast, and your sacrifice (Adha) is the day you sacrifice, and your gathering (Arafah) is the day you gather." The hadith of Abu Umair ibn Anas concerning the riders confirming the sighting the previous night and being commanded to pray the Eid the following morning supports this ruling, which Al-Khattabi deemed obligatory to follow as it is the established Sunnah and the hadith is authentic.