Mukhtasar Bukhari

Narrated from Sayyiduna Abu Hurairah (may Allah be pleased with him) that the Messenger of Allah (peace and blessings of Allah be upon him) said: "Whoever recites 'Subhan Allah wa bihamdihi' one hundred times in a day, all his sins will be erased, even if (his sins) are as much as the foam of the sea."