Rabbi Yisroel Lipkin of Salant
R’ Yisrael was once praising his student R’ Simcha Zissel Ziv of Kelm. Said a rabbi who was present, “If R’ Simcha Zissel would devote his talents completely to Gemora, instead of spending time also on Mussar, he would become a tremendous goan.”

“The Shulchan Oruch,” answered R’ Yisroel, “teaches that if a person has before him a small, perfect challah and a large but imperfect one, he must cut the perfect challah first. Similary, spritual perfection takes priority over scholarly greatness.”

From Sparks of Mussar by R Chaim Ephraim Zaitchik