Umar ibn Al-Khattab, may Allah be pleased with him, said to Abdullah ibn Salam, 'Who are the knowledgeable ones?' He replied, 'Those who act upon what they know.' Umar then asked, 'What removes knowledge from the hearts of men?' Abdullah ibn Salam replied, 'Greed.'
أَنَّ عُمَرَ بْنَ الْخَطَّابِ عَلَيْهِ رِضْوَانُ اللَّهِ تَعَالَى قَالَ لِعَبْدِ اللَّهِ بْنِ سَلَامٍ: مَنْ أَرْبَابُ الْعِلْمِ؟ قَالَ الَّذِينَ يَعْمَلُونَ بِمَا يَعْلَمُونَ قَالَ: فَمَا يَنْفِي الْعِلْمَ مِنْ صُدُورِ الرِّجَالِ؟ قَالَ: الطَّمَعُ