Hebrews 5:9-10
5:9 And by being perfected in this way, he became the source of eternal salvation to all who obey him,
5:10 and he was designated by God as high priest in the order of Melchizedek.
Hebrews 5:13-14
5:13 For everyone who lives on milk is inexperienced in the message of righteousness, because he is an infant.
5:14 But solid food is for the mature, whose perceptions are trained by practice to discern both good and evil.