Once, a merchant approached Reb Yisroel Salanter with the following dilemma:[1]
“I am very busy in my work,” said the man, “and I only have time to study for one hour; what is the best thing to study in that hour—Talmud, Halacha (Jewish law and custom) or Mussar (ethics)?”
Reb Yisroel wisely responded:
“You should study Mussar, for if you do, you will find another three hours for additional study.”
[1] Otzar Pitgamim VeSichot, Vol. 2, Pg. 25