Muwatta Malik 1039
موطأ مالك#1039SahihThese are the words of a Companion, not of the Prophet ﷺ. The chain is graded on its own terms.
وَحَدَّثَنِي يَحْيَى، عَنْ مَالِكٍ، عَنْ نَافِعٍ، أَنَّ عَبْدَ اللَّهِ بْنَ عُمَرَ، قَالَ الأَضْحَى يَوْمَانِ بَعْدَ يَوْمِ الأَضْحَى . وَحَدَّثَنِي عَنْ مَالِكٍ، أَنَّهُ بَلَغَهُ عَنْ عَلِيِّ بْنِ أَبِي طَالِبٍ، مِثْلُ ذَلِكَ
Yahya related to me from Malik from Nafi that Abdullah ibn Umar said, "The sacrifice can be done up to two days after the Day of Sacrifice." Yahya related to me from Malik that he had heard the same from Ali ibn Abi Talib
Scholarly Authentication
The label above is the grade most of these scholars gave — one dissenting opinion no longer speaks for all of them. If any scholar calls a narration fabricated, that verdict is shown instead, whatever the others say. Each scholar's own wording:
In-book reference: 23:12