مُسْنَدُ أَحْمَدَ
Musnad Ahmad 3404
Musnad of 'Abdullah bin al-'Abbas bin 'Abdul-Muttalib from the Prophet
It was narrated that Ibn Abi Mulaikah said: I wrote to Ibn 'Abbas and he wrote to me saying: The Messenger of Allah (ﷺ) said: "The one against whom a claim is made should swear an oath. If people were given in accordance with their claims, some people would make claims against others' wealth and lives.”
Musnad Ahmad 3427lts isnad is saheeh, al-Bukhari (2514) and Muslim (1711)]