Sayyidah Umm Hani (may Allah be pleased with her) said: O Messenger of Allah, I have grown old and weak, so teach me a supplication by which I may attain (the reward). The Messenger of Allah (peace and blessings be upon him) said: "O Umm Hani, if you say Subhan Allah one hundred times, it is better than freeing one hundred slaves. If you say al-Hamdu lillah one hundred times, it is better than one hundred horses that you give (to the fighters) to ride in the path of Allah. And if you say La ilaha illallah one hundred times, no deed will surpass it, and no sin will remain along with it."
Hadith Referenceالمعجم الكبير للطبراني / مسند النساء / 21439