Musnad Ahmad 27:1654

Ali ibn 'Asim narrated to us, from Yunus ibn 'Ubayd, al-Hasan informed us, from Ibn 'Umar, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "No servant swallows a gulp more excellent in the sight of Allah, the Almighty and Majestic, than a gulp of rage which he suppresses, seeking the Countenance of Allah, the Exalted."