Musannaf Ibn Abi Shayba 23:135

Zayd ibn al-Hubab narrated to us, from al-Sa'q ibn Hazn, he said: 'Aqil ibn al-Ja'd narrated to me, from Abu Ishaq, from Suwayd ibn Ghaflah, from Ibn Mas'ud, he said: The Messenger of Allah (may Allah bless him and grant him peace) said: "The firmest handhold of faith is love for the sake of Allah and hatred for the sake of Allah."