you have mentioned this hadith and i want it reference and authenticity . the hadith is "Sa‘eed ibn Jubayr, may Allaah be pleased with him, once asked Ibn ‘Abbaas, may Allaah be pleased with them both, whether or not he was obligated to enjoin the ruler to do what is good, and forbid him from doing what is evil. Ibn ‘Abbaas, may Allaah be pleased with them both, answered that if he feared he would be killed, he was not obliged to do so. Ibn Jubayr, may Allaah be pleased with him, repeated the same question thrice and every time Ibn ‘Abbaas’ answer was the same, but he added that if it was inevitable, he should advise him privately."

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.

This Hadeeth was reported by Sa’eed ibn Mansoor in his Sunan and by Al-Bayhaqi in Shu’ab Al-Eemaan, and by Abu Bakr ibn Abi Shaybah in his Musannaf but with the wording: “…..a man said to Ibn ‘Abbaas…...”. We have not come across any scholar who either classified it as Saheeh (sound) or as Dha’eef (weak).

However, many scholars tend to provide it as evidence and this suggests that it is authentic according to them, or that the wording that it contains is confirmed in other authentic Ahaadeeth, like the one reported by Ibn Abi ‘Aasim in his book entitled "As-Sunnah" from ‘Iyaadh ibn Ghanm that the Prophet said: ''Whoever wants to give advice to the Sultan (leader/ruler), he should not do that in public but he should take him by the hand and go into seclusion with him. If the ruler accepts his advice, then that is good and this is what is required, and if not, he (the adviser) has fulfilled his obligation.” [classified as Saheeh by Al-Albaani in Thilaal Al-Jannah]

Allaah Knows best.