مُسْنَدُ أَحْمَدَ
Musnad Ahmad 2676
Musnad of 'Abdullah bin al-'Abbas bin 'Abdul-Muttalib from the Prophet
A similar report was narrated from Anas bin Malik (رضي الله عنه) from the Prophet (ﷺ) except that he said in the first instance: "Whoever has in his heart faith the weight of a grain of barley"; in the second instance he said "wheat”; and in the third instance he said “corn."
Musnad Ahmad 2693Its isnad is saheeh]