It is reported that Mālik ibn Dīnār (rahimahullāh) said,
If a man seeks knowledge to act upon it, his knowledge will make him happy. And if he seeks knowledge, for other than acting upon it, his knowledge increases him in haughtiness.
عن أبي العالية قال : كان أبي صاحب عبادة ، فلما احتاج الناس إليه ، ترك العبادة وجلس للقوم
On Authority of Abī Ā’liyah
Ubayy ibn K’ab used to be a person of worship, and when the people were in need of him (due to his knowledge and high position amongst the companions) he would leave worship and sit with the people. (to answer their questions).
[Siyar ‘Alām An-Nubalā Volume 3, page 399].
The noble Companion of the Messenger of Allah – from the Ansār and those who partook in the Battle of Badr.
He was from the few who had memorised the whole Qur’ān in the lifetime of the Prophet – sallallāhu alayhi wa sallam -whom he ordered the people to take the Qur’ān from.
The Messenger of Allah said to him, “O Abā Mundhir (Ubay)! Do you know which verse from the Book of Allah – (you have memorised) with you – is the greatest?” He (Ubay) said, “Allah and His Messenger know best”. The Prophet (repeated and) said, “O Aba Mundhir (Ubay)! Do you know which verse from the Book of Allah – (you have memorised) with you – is the greatest?”. He (Ubay) said, “Allāhu laa ilāha illa huwal-Hayyul-Qayyoom … (āyatul-Kursi).He (Ubay) said, “He (The Prophet) then struck me on my chest and said “By Allah, may you be blessed in your knowledge O Aba Mundhir.” [Muslim, hadith no.810
On another occasion, the Prophet said to Ubay ibn K’ab, “Indeed Allah has commanded me to read the Qur’aan to you. He (Ubay) said, “Did He mention me by name?” He (the Prophet) said, “yes”. He (Ubay) said, “I was mentioned by the Lord of the Worlds?!” He said, “yes”. So Ubay began to shed tears. [Al-Bukhaari, hadith no.4961 and Muslim, hadith no. 799].
I did not write a single hadeeth except verily I acted on it, to the extent that it came to me that the Prophet (sallallaahu alaihi wa sallam) was cupped and gave Abaa Tayba a deenar, so I was cupped and gave the cupper a deenar.
Sufyan ath Thawree: A single hadeeth from the Messenger of Allah did not reach me, except that I acted on it, even if it was only the once. Siyaar A’laam An-Nubalaa vol 7 page 242