the refreshing

Isaiah 28:9-13
Whom shall he teach knowledge?
and whom shall he make to understand doctrine?
them that are weaned from the milk,
and drawn from the breasts. 

For precept must be upon precept, precept upon precept;
line upon line, line upon line;
here a little, and there a little:
for with stammering lips and another tongue
will he speak to this people. 

To whom he said,
This is the rest wherewith ye may cause the weary to rest;
and this is the refreshing:
yet they would not hear. 

But the word of the Lord was unto them
precept upon precept, precept upon precept;
line upon line, line upon line;
here a little, and there a little;
that they might go, and fall backward,
and be broken, and snared, and taken.

In contrast to the unteachable prideful ones in Isaiah 28:1-8 who produce immature fruit, those who are teachable in knowledge and understanding of doctrine are mature [have been weaned from milk - note you must first be raised on the milk before you mature, those who are still on milk still have not been practicing the basics].

The crown of pride (ie: bible correctors) is contrasted with those who study God's words repeatedly line upon line, precept upon precept, here a little, there a little.

To contrary, the elders who are spiritually mature from laboring in the word and doctrine wear their gray hair as a crown of glory.

Proverbs 16:31 The hoary head is a crown of glory, if it be found in the way of righteousness.

1 Tim 5:17 Let the elders that rule well be counted worthy of double honour, especially they who labour in the word and doctrine.

Notice to that the refreshing (the Holy Spirit) in v11-12 is in between studying God's words in v10 and v13.