Hadith: Whoever says (upon leaving his house) "In the name of Allah; I rely on Allah; there is no might and no power save in Allah", it will be said to him: "You are guided, sufficed, and protected", and the devil will go far away from him

عن أنس بن مالك رضي الله عنه مرفوعًا: «من قال -يعني: إذا خَرج من بَيتِه-: بِسم الله تَوَكَّلتُ على اللهِ، وَلاَ حول ولا قُوَّة إِلَّا بالله، يُقَال له: هُدِيتَ وَكُفِيتَ وَوُقِيتَ، وَتَنَحَّى عَنه الشَّيطَان». زاد أبو داود: «فيقول -يعني: الشيطان- لِشَيطان آخر: كَيف لَك بِرَجلٍ قَد هُدِيَ وكُفِيَ ووُقِيَ؟».
[صحيح] - [رواه أبو داود والترمذي]

Anas ibn Mālik (may Allah be pleased with him) reported that the Prophet (may Allah's peace and blessings be upon him) said: "Whoever says (upon leaving his house) 'In the name of Allah; I rely on Allah; there is no might and no power save in Allah', it will be said to him: 'You are guided, sufficed, and protected', and the devil will go far away from him." The narration by Abu Dawūd has the following addition: "So he (the devil) says to another devil: How can you approach a man who has been guided, granted relief, and protected?”
Sahih/Authentic. - [At-Tirmidhi]

Explanation

The Messenger of Allah (may Allah's peace and blessings be upon him) informs us in this Hadīth that if someone leaves their house and says, "In the name of Allah; I trust in Allah; there is no might and no power save in Allah", an angel will call out to him, saying: O servant of Allah, you have been guided to the straight path, you have been sufficed against your worries, and you have been protected from your enemies. So the devil assigned to him will move away from him, and another devil will say to the former: How can you misguide someone who has been guided, sufficed, and protected from all of the devils! Because he said those words, you cannot overpower him.