Sayyiduna Abu al-Darda' (may Allah be pleased with him) reports this saying of the Prophet (peace and blessings be upon him): "Any servant who recites 'La ilaha illallah' (There is no deity except Allah) 100 times, when Allah Almighty raises him on the Day of Resurrection, his face will be like the moon on the fourteenth night, and on that day no one's deed that is more excellent than his deed will be raised up, except for one who recited this phrase as he did, or recited it more times."
Tabarani recorded it; its chain contains a narrator, Abd al-Wahhab bin al-Dahhak, who is matruk (abandoned).
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الأذكار / 16830