al-Khizr (AS) said to Prophet Moses (AS), ‘O Moses, devote yourself exclusively to knowledge if you want it, for verily knowledge is for the one who devotes himself exclusively to it.
الخِضرُ (عَلَيهِ الّسَلامُ) ـ لِموسى (عَلَيهِ الّسَلامُ) ـ: يا موسى ، تَفَرَّغْ لِلعِلمِ إن كُنتَ تُريدُهُ، فإنَّ العِلمَ لِمَن تَفَرَّغَ .