مُسْنَدُ أَحْمَدَ
Musnad Ahmad 4211
Musnad of Abdullah bin Mas'ood
It was narrated from Abu Ma'mar from ‘Abdullah. He (the narrator) said: I heard him attribute it to the Prophet (ﷺ) on one occasion, then he did not do that. He saw a governor or a man say two tasleems and he said: Where did he learn that?
Musnad Ahmad 4239Its isnad is saheeh, Muslim (581)]