Sa’id ibn Wahb reported: Abdullah ibn Mas’ud, may Allah be pleased with him, said, “People will continue to be virtuous as long as they take knowledge from the companions of Muhammad, peace and blessings be upon him, and their elders. If they take their knowledge from the young, that is when they will be ruined.”
Source: al-Zuhd wal-Raqā’iq 801
عَنْ سَعِيدِ بْنِ وَهْبٍ عَنْ عَبْدِ اللَّهِ بْنِ مَسْعُودٍ قَالَ رضي الله عنه لا يَزَالُ النَّاسُ بِخَيْرٍ مَا أَتَاهُمُ الْعِلْمُ مِنْ قِبَلِ أَصْحَابِ مُحَمَّدٍ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ وَأَكَابِرِهِمْ فَإِذَا أَتَاهُمُ الْعِلْمُ مِنْ قِبَلِ أَصَاغِرِهِمْ فَذَلِكَ حِينَ هَلَكُوا
801 الزهد والرقائق لابن المبارك