Abu Yusuf reported: Umar ibn al-Khattab, may Allah be pleased with him, said, “Know that Allah has servants who cause some falsehood to die out by ignoring it and they give life to the truth by mentioning it.”
Source: Kitāb al-Kharrāj 1/23
عن أبي يوسف عَنْ عُمَرَ بْنِ الْخَطَّابِ رَضِيَ اللَّهُ عَنْهُ قال وَاعْلَمُوا أَنَّ لِلَّهِ عِبَادًا يُمِيتُونَ الْبَاطِلَ بِهَجْرِهِ وَيُحْيُونَ الْحَقَّ بِذِكْرِهِ
1/23 كتاب الخراج