Imam Ahmad bin Hanbal (may Allah have mercy on him) says:

"قَلَّ رَجُلٌ يَأْخُذُ كِتَابًا يَنْظُرُ فِيهِ إِلَّا اسْتَفَادَ مِنْهُ شَيْئًا"

It rarely happens that a man picks up a book to look into it without gaining some benefit from it.

Meaning: Whenever you open a book, you surely obtain benefit from it. Therefore, keep reading books regularly.

(Al-Ilal wa Ma'rifat al-Rijal by Abdullah bin Ahmad bin Hanbal: 2393, contextual translation)