For it was fitting that he, for whom and through whom all things exist, in bringing many children to glory, should make the leader to their salvation perfect through suffering.

Now since the children share in blood and flesh, he likewise shared in them, that through death he might destroy the one who has the power of death, that is, the devil, and free those who through fear of death had been subject to slavery all their life.  Surely he did not help angels but rather the descendants of Abraham; therefore, he had to become like his brothers in every way, that he might be a merciful and faithful high priest before God to expiate the sins of the people.

Because he himself was tested through what he suffered, he is able to help those who are being tested.

Hebrews 2:10, 14-18