مُسْنَدُ أَحْمَدَ
Musnad Ahmad 3055
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) said: "There will emerge from 'Adan Abyan (a place in Yemen) twelve thousand who support (the religion of) Allah and His Messenger. They are the best of people between me and them." Ma'mar said to me: Go and ask him about this hadeeth.
Musnad Ahmad 3079Its isnad is saheeh]