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]

It is narrated by ‘Umar bin al-Khattāb that the Prophet (صلى الله عليه وآله وسلم) said:

"Among Allāh’s servants there are some who are neither prophets nor martyrs but on the Day of Judgement the prophets and the martyrs will envy their grades. The Companions asked: ‘O Messenger of Allāh, tell us, who are those people?’ He replied: ‘those are the people who love one another on Allāh’s count. They are neither related to one another nor do they have any property to exchange. I swear on Allāh that they will have faces of light,they will be on pulpits of light. They will not have any fear when others will be afraid, they will not have any grief when others will be aggrieved.’ Then he recited the verse: Beware! No doubt, there is no fear for the friends of Allāh nor shall they be sad and sorrowful. "

[Qur’ān (Yūnus, Jonah) 10:62.]

Abū Dāwūd, Sunan, b. of ijārah (wages) 3:288 (#3527); Bayhaqī, Shu‘ab-ul-īmān, (6:486#8998,8999); Khatīb Tabrīzī, Mishkāt-ul-masābīh, b. of adab (good manners) ch.16 (3:75-6#5012).  [src: Ch3 of Beseeching for Help, Tahir-ul-Qadri]