‘Iyad ibn Ghanam reported: The Messenger of Allah, peace and blessings be upon him, said, “Whoever has advice for the ruler, let him take his hand and give it privately. If he accepts it, then he accepts it. If he rejects it, the duty upon him has been fulfilled.”
Source: al-Sunnah li-Ibn Abī ‘Āṣim 1098
Grade: Sahih (authentic) according to Al-Albani
Imam Ibn Rajab commented, “The righteous predecessors, when they wished to advise someone, would admonish him privately, such that one of them said: Whoever admonishes his brother privately, then it is sincere advice. But whoever admonishes him in front of people has only humiliated and disgraced him.”
Source: Jāmi’ al-‘Ulūm wal-Ḥikam 1/225
عَنْ عِيَاضِ بْنِ غَنْمٍ قَالَ قَالَ رَسُولَ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ مَنْ كَانَتْ عِنْدَهُ نَصِيحَةٌ لِذِي سُلْطَانٍ فَلْيَأْخُذْ بِيَدِهِ فَلْيَخْلُو بِهِ فَإِنْ قَبِلَهَا قَبِلَهَا وَإِنْ رَدَّهَا كَانَ قَدْ أَدَّى الَّذِي عَلَيْهِ
1098 السنة لابن أبي عاصم باب كيف نصيحة الرعية للولاة
2/523 المحدث الألباني خلاصة حكم المحدث صحيح في تخريج كتاب السنة
قال ابن رجب وكان السلفُ أذا أرادوا نصيحةَ أحدِ وعظوه سرًا حتى قال بعضهم منْ وعظ أخاه فيما بينه وبينَه فهي نصيحة ومن وعظه على رؤوس الناس فإنما وبخه
1/225 جامع العلوم والحكم الحديث السابع