مُسْنَدُ أَحْمَدَ
Musnad Ahmad 2472
Musnad of 'Abdullah bin al-'Abbas bin 'Abdul-Muttalib from the Prophet
It was narrated that Ibn 'Abbas (رضي الله عنه) said: We were with the Prophet (ﷺ) on a journey, and the Day of Sacrifice came, so we slaughtered a cow on behalf of seven, and a camel on behalf of ten.
Musnad Ahmad 2484In its chain Hasan bin Yahya is uncertain]