Hadith: O boy, I shall teach you some words: Be mindful of Allah, and Allah will protect you. Be mindful of Allah, and you will find Him before you. If you ask, ask Allah; if you seek help, seek help from Allah

عن ابن عباس رضي الله عنهما قال:
كُنْتُ خَلْفَ رَسُولِ اللهِ صَلَّى اللهُ عَلَيْهِ وَسَلَّمَ يَوْمًا، فَقَالَ: «يَا غُلَامُ، إِنِّي أُعَلِّمُكَ كَلِمَاتٍ، احْفَظِ اللهَ يَحْفَظْكَ، احْفَظِ اللهَ تَجِدْهُ تُجَاهَكَ، إِذَا سَأَلْتَ فَاسْأَلِ اللهَ، وَإِذَا اسْتَعَنْتَ فَاسْتَعِنْ بِاللهِ، وَاعْلَمْ أَنَّ الْأُمَّةَ لَوِ اجْتَمَعَتْ عَلَى أَنْ يَنْفَعُوكَ بِشَيْءٍ، لَمْ يَنْفَعُوكَ إِلَّا بِشَيْءٍ قَدْ كَتَبَهُ اللهُ لَكَ، وَلَوِ اجْتَمَعُوا عَلَى أَنْ يَضُرُّوكَ بِشَيْءٍ، لَمْ يَضُرُّوكَ إِلَّا بِشَيْءٍ قَدْ كَتَبَهُ اللهُ عَلَيْكَ، رُفِعَتِ الْأَقْلَامُ وَجَفَّتِ الصُّحُفُ».
[صحيح] - [رواه الترمذي] - [سنن الترمذي: 2516]

Ibn ‘Abbās (may Allah be pleased with him) reported:
One day, I was riding behind the Prophet (peace and blessings of Allah be upon him), and he said: "O boy, I shall teach you some words: Be mindful of Allah, and Allah will protect you. Be mindful of Allah, and you will find Him before you. If you ask, ask Allah; if you seek help, seek help from Allah. And know that if the Ummah were to gather together to benefit you with anything, they would not benefit you except with what Allah had already prescribed for you. And if they were to gather together to harm you with anything, they would not harm you except with what Allah had already prescribed against you. The pens have been lifted, and the scrolls have dried."
[Authentic hadith] - [Narrated by At-Termedhy] - [Sunan At-Termedhy - 2516]

Explanation

Ibn ‘Abbās (may Allah be pleased with him) informs that one day, as a boy, he was riding behind the Prophet (may Allah's peace and blessings be upon him), and he said to him: I will teach you things by which Allah will benefit you:
Be mindful of Allah by observing His commands and prohibitions so He will find you engaged in the acts of worship and piety and not find you committing sins and misdeeds. If you do so, your recompense will be that Allah will protect you from unpleasant things in this world and the Hereafter and support you in your endeavors wherever you go.
If you want to ask for something, do not ask anyone but Allah, for He alone responds to those who ask.
And if you need help, do not seek help except from Allah.
And you should be certain that no benefit will come to you, even if all the earth's inhabitants were to gather together to bring it to you, except if Allah had predestined it for you. No harm will happen to you, even if all the inhabitants of the earth were to gather together to cause it to you, except if Allah had predestined it for you.
And that Allah Almighty had written and predestined this matter according to His wisdom and knowledge, and whatever Allah had written cannot be changed.