مُسْنَدُ أَحْمَدَ
Musnad Ahmad 4144
Musnad of Abdullah bin Mas'ood
It was narrated from 'Abdullah that The Prophet (ﷺ) said: "(Believing in) bird omens is shirk. There is no one among us who does not (think of them), but Allah takes away (such thoughts) by means of putting trust in Him.”
Musnad Ahmad 4171lts isnad is saheeh]