مُسْنَدُ أَحْمَدَ
Musnad Ahmad 2379
Musnad of 'Abdullah bin al-'Abbas bin 'Abdul-Muttalib from the Prophet
It was narrated that Ibn 'Abbas (رضي الله عنه) said: The Messenger of Allah (ﷺ) walked with them to Baqee' al-Gharqad, then he sent them off and said: "March forth in the Name of Allah.” And he said: “O Allah, help them," meaning the group that he sent to Ka'b bin al-Ashraf.
Musnad Ahmad 2391Its isnad is hasan]