‘Abdallah b. Mas'ud said:

If the learned were to guard learning and entrust it to those who are worthy of it, they would thereby, rule their contemporaries. But they have bestowed it on worldly people to get thereby some of their worldly goods, and have been despised by them. I heard your Prophet (ﷺ) say, "If anyone makes the care of his eternal welfare the sum total of his cares God will protect him from worldly care, but if he has a variety of cares consisting of matters related to this world God will not be concerned in which of its <i>wadis</i> he perishes.” Ibn Majah transmitted it, and Baihaqi transmitted it in <i>Shu'ab al-iman</i> from Ibn ‘Umar beginning with "If anyone makes the care.”

وَعَنْ عَبْدِ اللَّهِ بْنِ مَسْعُودٍ قَالَ: لَوْ أَنَّ أَهْلَ الْعِلْمِ صَانُوا الْعِلْمَ وَوَضَعُوهُ عِنْدَ أَهْلِهِ لَسَادُوا بِهِ أَهْلَ زَمَانِهِمْ وَلَكِنَّهُمْ بَذَلُوهُ لِأَهْلِ الدُّنْيَا لِيَنَالُوا بِهِ مِنْ دُنْيَاهُمْ فَهَانُوا عَلَيْهِمْ سَمِعْتُ نَبِيَّكُمْ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ يَقُولُ: «مَنْ جَعَلَ الْهُمُومَ هَمًّا وَاحِدًا هَمَّ آخِرَتِهِ كَفَاهُ اللَّهُ هَمَّ دُنْيَاهُ وَمَنْ تَشَعَّبَتْ بِهِ الْهُمُومُ فِي أَحْوَالِ الدُّنْيَا لَمْ يُبَالِ اللَّهُ فِي أَيِّ أَوْدِيَتِهَا هَلَكَ» . رَوَاهُ ابْنُ مَاجَه وَرَوَاهُ الْبَيْهَقِيُّ فِي شُعَبِ الْإِيمَانِ عَنِ ابْنِ عُمَرَ مِنْ قَوْلِهِ: «مَنْ جَعَلَ الْهُمُومَ» إِلَى آخِره