What is the authenticity of raising the best deeds by uttering the Shahada one hundred times?

The word of testimony, "Lā ilāha illā Allāh" (There is no god but Allah), is the best remembrance (dhikr) after the Noble Qur'an, and saying it a hundred times is permissible. The proof for this is the hadith narrated by Umm Hani bint Abi Talib (may Allah be pleased with her), that the Prophet (peace be upon him) said to her: "Glorify Allah a hundred times (by saying 'Lā ilāha illā Allāh'); it will fill what is between the heaven and the earth, and no one's deed will be raised on that day except if he comes with the like of what you have come with." This hadith was narrated by Imam Ahmad and authenticated by Al-Albani.