بسم الله الرحمن الرحيم
Ibn Al-Qayyim – rahimahu Allah said:
Likewise, from among them [i.e. the causes that alleviate the chest] is knowledge. For it truly alleviates the chest, expanding it until it becomes more expansive than the whole world. As for ignorance, it brings about tightening, confinement and repression.
So whenever the knowledge of the servant broadens, his chest likewise broadens and expands. However, this is not applicable to all fields of knowledge. Rather, it is [specific] to the bequeathed knowledge left by the Messenger ﷺ, which is the beneficial form of knowledge.
Therefore, its people [i.e. the people of knowledge] possess the most alleviated chests amongst humankind, the most expansive of hearts among them, the best of them in character, of those living the pleasantest of lives.
Source: Ibn Al-Qayyim, Zaad Al-Ma’aad, Chapter: Concerning the causes of alleviating the chest, [of which] complete and perfect acquisition belongs to him [i.e. the Messenger] ﷺ