On the authority of Abu Abbas Abdullah bin ‘Abbaas (may Allaah be pleased with him) who said:
One day I was behind the Prophet (peace and blessings of Allaah be upon him) [riding on the same mount] and he said, “O young man, I shall teach you some words [of advice]: Be mindful of Allaah and Allaah will protect you. Be mindful of Allaah and you will find Him in front of you. If you ask, then ask Allaah [alone]; and if you seek help, then seek help from Allaah [alone]. And know that if the nation were to gather together to benefit you with anything, they would not benefit you except with what Allaah 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 Allaah had already prescribed against you. The pens have been lifted and the pages have dried.”
[at-Tirmidhee (#2516) and Shaykh al-Albaanee declared it to be authentic]
Subhaan Allaah, this is one of my favorite ahadiths and a great advice to give to our children, to teach them Tawheed and the correct ‘Aqeedah!