John was born a stranger to the world of children who used to amuse themselves, as he was serious all the time. Most children took delight in torturing animals whereas, he was merciful to them. He fed the animals from his food until there was nothing left for him, and he just ate fruit or leaves of trees.
John loved reading since childhood. When he grew up, Allah the Exalted called upon him: "O John! Hold fast to the Scripture (The Torah)." And We gave him wisdom while yet a child. Surah 19: 12
Related Quran Ayaaths of this Hadith.
"When a person dies, his works end, except for three: ongoing charity, knowledge that is benefited from, and a righteous child who prays for him."
Prophet Mohammed (PBUH)
"The best of what a man leaves behind are three: a righteous child who supplicates for him, ongoing charity the reward of which reaches him, and knowledge that is acted upon after him."
Sunan Ibn Mājah
"Every day two angels come down from Heaven and one of them says, 'O Allah! Compensate every person who spends in Your Cause,' and the other (angel) says, 'O Allah! Destroy every miser.'"
Sahih Bukhari