ISB ~ Hebrews 5 v8

learned obedience:Not by trial and error, but from the experience of passing through the human trials and ordeals that test our commitment to God.

• Christ, being eternally divine, possessed the fullness of knowledge from the first instant of his conception as a man. He was ignorant of nothing, so he could not learn anything new by simple recognition. But there is also knowledge acquired by experience, and in this sense he learned obedience through what he suffered. Having accepted our weakness, he learned how difficult it is to obey, for he obeyed in the most difficult of circumstances, even unto death on a cross (St. Thomas Aquinas, Commentary on Hebrews 5, 2).