It is narrated from Sayyiduna Abu Hurayrah (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "Whoever says 'La ilaha illallah' (there is none worthy of worship except Allah), it will certainly benefit him on some day of his life, even if it is after punishment has afflicted him."
Imam al-Tabarani (may Allah have mercy on him) said: "This hadith is narrated from Ubaydullah bin Abdullah (may Allah have mercy on him) only through this chain."
Hadith Referenceالمعجم الأوسط / باب الحاء / 3486
Hadith Takhrij«أخرجه ابن حبان فى «صحيحه» برقم: 3004، والبزار فى «مسنده» برقم: 8292، وعبد الرزاق فى «مصنفه» برقم: 6045، والطبراني فى «الصغير» برقم: 393، والطبراني فى «الأوسط» برقم: 6396»