مُسْنَدُ أَحْمَدَ
Musnad Ahmad 3838
Musnad of Abdullah bin Mas'ood
It was narrated that 'Abdullah bin Masood (رضي الله عنه) said: Whilst we were with the Messenger of Allah (ﷺ) on one of his journeys, we heard a caller calling: Allahu Akbar, Allahu Akbar. The Prophet Allah (ﷺ) said: “In a state of fitrah (sound human nature).” He said: I bear witness that there is no God but Allah. The Prophet of Allah (ﷺ), said: “He has escaped the Fire.” We rushed to see who it was, and it was a man tending a flock of sheep; the time for prayer had come and he gave the call for it.
Musnad Ahmad 3861Its isnad is saheeh]