It is reported that ʿAbdullāh b. ‘Abbās – Allāh be pleased with him – said, “Love for Allāh and hate for Allāh, make your enmity because of Allāh and your allegiance because of Allāh; for indeed, the love and support of Allāh is not achieved save through this. And a man will never taste true faith (īmān) – though he may pray and fast much – except when he is like that. Today, the people’s brotherhood is based upon worldly considerations (dunyā), but this will not do anything for them on the Day of Resurrection.”
Ibn Al-Mubārak, Al-Zuhd wa Al-Raqā`iq article 353.