Narrated ‘Aisha رضي الله عنه :
The Prophet صل الله عليه و سلم sent (an army unit) under the command of a man who used to lead his companions in the prayers and would finish his recitation with (the Sura 112): ‘Say (O Muhammad): “He is Allah, the One.” ‘ (112.1) When they returned (from the battle), they رضي الله عنهم mentioned that to the Prophet صل الله عليه و سلم. He صل الله عليه و سلم said (to them), “Ask him why he does so.” They رضي الله عنهم asked him and he said, “I do so because it mentions the qualities of the Beneficent and I love to recite it (in my prayer).” The Prophet صل الله عليه و سلم said (to them), “Tell him that Allah loves him”
[Sahih Bukhari Volume 9, Book 93, Number 472]
This is just a beautifully simply hadith. It speaks to the importance of sincerity, how sincerity can have the most unintended of beautiful consequences.