Muhammad (the Apostle) p.b.u.h. said:
When a man dies all except three of his works perish, namely, a permanent endowment for charity, useful knowledge, and righteous progeny that bring honor upon his memory.
Envy is unlawful except regarding two categories of persons, those to whom G-d has given wealth and power to spend that wealth rightly, and those to whom G-d has given wisdom with which they regulate (their lives) and which they teach.
It has been said (in the process of learning) the first (step) is silence, followed by listening, then retention, then doing, and finally imparting.
It has also been said, “Teach what you know to him who does not know and learn from him who knows what you do not know. If you would do this you would learn what you have not known and would retain what you have already known.” —Ali R. Muhammad contributed the verse.