A man said to the Prophet (peace be upon him): By Allah, O Messenger of Allah, I do love you. The Prophet (peace be upon him) said: Look, what you are saying? The man said: By Allah, I love you, and repeated this sentence thrice. The Prophet (peace be upon him) said: If you really love me, then be prepared for acute poverty, for extreme hardship rushes more rapidly towards a person who loves me, than a flood flows towards its goal. "
(Narrated Abdullah ibn Mughaffal - al-Tirmidhi) [src: alim.org]