In The Name of Allaah, The Most Merciful, The Bestower of Mercy
A man came to Ibn Mas’ood [radiyallaahu-anhu] and said, ‘’Teach me [some] comprehensive and beneficial statements’’. So he said, ‘’Worship Allaah and do not associate anything with Him [in worship]; be with the Qur’aan wherever it is [i.e. be in agreement with it in all circumstances]. Whoever comes to you with truth – whether he is young or old, and even if he is not close to you and is hated to you, then accept it from him. And whoever comes to you whilst lying, then reject it, even if he is beloved and close to [you]’’.
[Source: مساوئ الأخلاق ومذمومها – page 72. By Abubakr Muhammad Bin Jafar Bin Sahl Ash-Shaamiriy (rahimahullaah); Born 240AH and died 327AH]