On the authority of Abu Malik al-Harith bin Asim al-Asharee (may Allah be pleased with him) who said:
The Messenger of Allah (peace and blessings of Allah be upon him) said, "Purity is half of iman (faith). 'Al-hamdu lillah (praise be to Allah)' fills the scales, and 'subhan-Allah (how far is Allah from every imperfection) and 'Al-hamdulillah (praise be to Allah)' fill that which is between heaven and earth. And the salah (prayer) is a light, and charity is a proof, and patience is illumination, and the Qur'an is a proof either for you or against you. Every person starts his day as a vendor of his soul, either freeing it or causing its ruin."[Muslim]
Reference: 40 Hadith Nawawi 23
English translation: Hadith 23