Authentic Supplication Number 006.

The Messenger of Allah  said: "Whoever says: La 'ilaha 'illa 'allahu wahdahu la shareeka lahu, lahulmulku wa lahul hamdu wa huwa `ala kulli shay'in qadeerun (7).

100 times would get the reward of manumitting ten slaves, one hundred good deeds would be written for him, one hundred sins would be remitted from him, it would be a shield for him from the Shaytan that day till night, and nobody would arrive with better than what he arrived with except for one that had done more than him."

Footnotes.
(6) Tahmeed is to say 'Al-hamdu lillahi, Tahleel is to say La 'ilaha 'illa 'allahu, and Tasbeeh is to say Subhana 'allahi.

(7) There is no 'ilah except Allah, no partner does He have; his is the Kingdom, and to Him is all Praise, and He is ever-able to do everything.

Reporters.
Reported in Saheeh 'Al-Bukhari and Saheeh Muslim. 'Al-Albani included this hadeeth in The Authentic of Good Sayings as #6.