preach the word [as an official messenger]; be ready when the time is right and even when it is not [keep your sense of urgency, whether the opportunity seems favorable or unfavorable, whether convenient or inconvenient, whether welcome or unwelcome]; correct [those who err in doctrine or behavior], warn [those who sin], exhort and encourage [those who are growing toward spiritual maturity], with inexhaustible patience and [faithful] teaching.

With

for He was teaching them as one who had authority [to teach entirely of His own volition], and not as their scribes [who relied on others to confirm their authority].

They were completely amazed at His teaching; because He was teaching them as one having [God-given] authority, and not as the scribes.

They were all astonished and in awe, and began saying to one another, “What is this message? For with authority and power He commands the unclean spirits and they come out!”

Let

Let no one look down on [you because of] your youth, but be an example and set a pattern for the believers in speech, in conduct, in love, in faith, and in [moral] purity.

General references

and they were surprised [almost overwhelmed] at His teaching, because His message was [given] with authority and power and great ability.

Keep commanding and teaching these things.

Keep instructing [the people to do] these things as well, so that they may be blameless and beyond reproach.