Ibn Abbas reported: I was riding with the Messenger of Allah, peace and blessings be upon him, and he said:
يَا غُلَامُ إِنِّي أُعَلِّمُكَ كَلِمَاتٍ احْفَظْ اللَّهَ يَحْفَظْكَ احْفَظْ اللَّهَ تَجِدْهُ تُجَاهَكَ إِذَا سَأَلْتَ فَاسْأَلْ اللَّهَ وَإِذَا اسْتَعَنْتَ فَاسْتَعِنْ بِاللَّهِ وَاعْلَمْ أَنَّ الْأُمَّةَ لَوْ اجْتَمَعَتْ عَلَى أَنْ يَنْفَعُوكَ بِشَيْءٍ لَمْ يَنْفَعُوكَ إِلَّا بِشَيْءٍ قَدْ كَتَبَهُ اللَّهُ لَكَ وَلَوْ اجْتَمَعُوا عَلَى أَنْ يَضُرُّوكَ بِشَيْءٍ لَمْ يَضُرُّوكَ إِلَّا بِشَيْءٍ قَدْ كَتَبَهُ اللَّهُ عَلَيْكَ رُفِعَتْ الْأَقْلَامُ وَجَفَّتْ الصُّحُفُ
Young man, I will teach you some words. Be mindful of Allah and He will protect you. Be mindful of Allah and you will find Him before you. If you ask, ask from Allah. If you seek help, seek help from Allah. Know that if the nations gathered together to benefit you, they could not benefit you unless Allah has decreed it for you. And if the nations gathered together to harm you, they could not harm you unless Allah has decreed it for you. The pens have been lifted and the pages have dried.
Sunan al-Tirmidhī 2516, Grade: Sahih