Musannaf Ibn Abi Shayba 30:143

Muhammad ibn Bishr narrated to us, he said: Abd al-Aziz ibn Umar narrated to us, he said: Ibrahim ibn Abi Abla al-Uqayli narrated to me that al-Ala ibn Ziyad used to narrate from the Prophet of Allah, may Allah bless him and grant him peace, that he said: "There are servants from among the servants of Allah who are neither prophets nor martyrs, yet the prophets and the martyrs will envy them on the Day of Resurrection due to their closeness to Allah, upon pulpits of light. The prophets and the martyrs will say: 'Who are these?' They will say: 'These are those who used to love one another for the sake of Allah, without any wealth they exchanged between them, and without any kinship that existed between them.'"