[Commentary]
One of the clearest proofs of the excellence of knowledge—both acquiring it and teaching it for Allah’s sake—is the report the author, may Allah have mercy on him, cites from Abū Hurayrah, may Allah be pleased with him. The Prophet ﷺ said: “Whoever seeks knowledge that is ordinarily pursued for the sake of Allah’s Face, yet he only desires thereby some worldly gain, will not smell the fragrance of Paradise on the Day of Resurrection,” meaning its scent.

Knowledge is of two kinds. The first is knowledge sought for Allah’s sake: the Islamic sciences and the Arabic disciplines that support them. The second is worldly knowledge, such as engineering, construction, mechanics, and the like.

With regard to the second kind—worldly knowledge—there is no harm in studying it for worldly benefit. A person may learn engineering so as to become an engineer who earns a salary and receives payment; he may study mechanics so as to work as a mechanic, laboring for a living and intending nothing beyond worldly profit. There is no sin in intending the world alone through such study. Yet if he were to intend, through what he learns, to benefit the Muslims, that would be better for him, and he would thereby obtain both religious and worldly reward. For instance, were he to say, “I want to study engineering so that the Muslims will not have to hire non-Muslim engineers,” that would be commendable. Or if he studied mechanics in order to meet the Muslims’ needs whenever they require mechanics, that too would be good, and he would be rewarded for it. However, if he seeks only worldly advantage, that is his choice and he incurs no sin.