مُسْنَدُ أَحْمَدَ
Musnad Ahmad 3698
Musnad of Abdullah bin Mas'ood
It was narrated from Abu ‘Ubaidah and Abul-Ahwas, who said: This is the hadeeth of Abu ‘Ubaidah from his father, who said: The Messenger of Allah (ﷺ) taught us two khutbahs, khatbatal-hajah and khutbatas-salah (i.e., "at-tahiyyatu..."): "‘Praise be to Allah' or ‘Verily praise is to Allah we seek His help…’” And he mentioned a similar report.
Musnad Ahmad 3721The isnad via Abu 'Ubaidah – i.e. Ibn ’Abdullah bin Mas'ood