Muwatta Malik 868
موطأ مالك#868SahihThese are the words of a Companion, not of the Prophet ﷺ. The chain is graded on its own terms.
وَحَدَّثَنِي عَنْ مَالِكٍ، عَنْ نَافِعٍ، أَنَّ عَبْدَ اللَّهِ بْنَ عُمَرَ، كَانَ يَقُولُ {مَا اسْتَيْسَرَ مِنَ الْهَدْى} بَدَنَةٌ أَوْ بَقَرَةٌ .
Yahya related to me from Malik from Nafi that Abdullah ibn Urnar used to say, "The least thing that is acceptable as a sacrificial animal is a camel or a cow
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:
Salim al-HilaliMauquf Sahih
In-book reference: 20:164