Hadith 17:225
Abu Usama narrated to us, from al-Mujalid, who said: Amir informed me, from Ibn Abbas, who said: Al-Abbas said to his son, Abdullah: "O my son, I see the Commander of the Faithful bringing you near and consulting you along with people from the companions of the Messenger of Allah (may Allah bless him and grant him peace), and he is alone with you. So memorize three things from me: Fear Allah, let him never experience a lie from you, do not disclose any of his secrets, and do not criticize anyone in his presence." He (the narrator) said: So I said to Ibn Abbas: "O Abu Abbas, each one of them is better than a thousand." He said: "And better than ten thousand."
حدثنا أبو أسامة عن المجالد قال أخبرني عامر عن بن عباس قال قال العباس لابنه عبد الله يا بني إني أرى أمير المؤمنين يقربك ويستشيرك مع أناس من أصحاب رسول الله صلى الله عليه وسلم ويخلو بك فاحفظ عني ثلاثا اتق الله لا يجربن عليك كذبة ولا تفشين له سرا ولا تعاتبن عنده أحدا قال فقلت لابن عباس يا أبا عباس كل واحدة منهن خير من ألف قال ومن عشرة آلاف