Sayyiduna Anas bin Malik (may Allah be pleased with him) says that the Messenger of Allah (peace and blessings be upon him) said: "Whoever says: 'In the name of Allah, I have put my trust in Allah, and there is no power to avoid sin nor strength (to do good) except with the help of Allah,' it is said (to him): 'You have been protected and you have been sufficed.'"
Hajjaj bin Muhammad also narrated it from Ibn Jurayj and added in it: "when he goes out of his house."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الحج / 10310