Imam Khomeini always sought to guide his seminary students as while conducting classes he would say:
“Purify your soul. Cultivation of morals comes before the science of (spiritual) purification; and if a person wishes to make use of his knowledge, he must first be spiritually purified.”
Narrated by: Ayatollah Mohammad Reza Tawassoli
Taken from: Keeping Pace with the Sunlight, vol. 1, p. 272