Al-Haytam ibn Jamil reported: I said to Malik, “O servant of Allah, if a man has knowledge of the Sunnah, should he argue to defend it?” Malik, may Allah have mercy on him, said, “No, rather he should convey the Sunnah if they might accept it from him, otherwise he should remain silent.”
Source: Jāmi’ al-‘Ulūm wal-Ḥikam 1/248
قَالَ الْهَيْثَمُ بْنُ جَمِيلٍ قُلْتُ لِمَالِكٍ يَا أَبَا عَبْدِ اللَّهِ الرَّجُلُ يَكُونُ عَالِمًا بِالسُّنَنِ يُجَادِلُ عَنْهَا قَالَ رحمه الله لَا وَلَكِنْ يُخْبِرُ بِالسُّنَّةِ فَإِنْ قُبِلَ مِنْهُ وَإِلَّا سَكَتَ
1/248 جامع العلوم والحكم الحديث التاسع ما نهيتكم عنه فاجتنبوه