'Abdullah ibn Mughaffal said, "A man said to the Prophet, may Allah bless him and grant him peace, "Messenger of Allah, by Allah, I love you." He said, "Be careful of what you say." He said, "By Allah, I love you," three times. He said, "If you love me, then prepare yourself for poverty. Poverty comes swifter to the one who loves me than a flood to its destination."
Riyadh-as-Saliheen by Imam Al-Nawawi, volume 3, hadith number 484 - Sunni Hadith