Three times:
بِسْمِ اللَّهِ الَّذِيْ لَا يَضُرُّ مَعَ اسْمِهِ شَيْءٌ فِي الْأَرْضِ وَلَا فِي السَّمَاءِ وَهُوَ السَّمِيعُ الْعَلِيمُ
Transliteration
Bismillaahil-lathee laa yadhurru ma'as-mihi shay'un fil-'ardhi wa laa fis-samaa'i wa Huwas-Samee 'ul- 'Aleem.
Translation
In the name of Allah with whose name nothing is harmed on earth nor in the heavens and He is The All-Seeing, The All-Knowing.
Note
Uthman (RA) say: I heard the Messenger of Allah (ﷺ) say: If anyone says three times: "In the name of Allah, when Whose name is mentioned nothing on Earth or in Heaven can cause harm, and He is the Hearer, the Knower" he will not suffer sudden affliction till the morning, and if anyone says this in the morning, he will not suffer sudden affliction till the evening.
Say this morning and evening - Allah keeps you safe. It's like a shield. Sudden harm cannot touch you. The All-Hearing Lord watches over you every day.
After Fajr in the morning. After Asr in the evening. This keeps you safe all day and all night.
Three times. Hadith says so. Say it thrice morning and evening - nothing harms you.
Yes. The Prophet ﷺ said: say this three times - sudden trouble will not touch you until next morning.
There are specific ayats. But this morning and evening dua is very strong. It protects from all harm - evil eye, magic, bad intentions.
Yes. Phone or paper - both fine. Most important: understand the meaning. Trust Allah.
Hifazat ki dua means safety prayer. In Allah's name, nothing harms you on earth or in sky. He is All-Hearing, All-Knowing.
Yes. Very simple. Easy to remember. Teach your kids. They stay under Allah's care at school or play.
Send Blessings on the Prophet ﷺ - Morning & Evening
Top Dhikr and Dua (Tasbih)
Glory and Praise to Allah - Subhanallahi Wa Bihamdihi (Forgiveness Dua)
Ask Allah to Forgive and Keep You Safe
Ask for Safety in This Life and the Next (Masnun Dua)
Ask Allah's Protection from the Dark Moon