Line 13 premises on the dissemination or impact of knowledge as the peak of its importance. Al-Sahili says knowledge impacted in others increase while its hoarding decrease it values.
Hammad Ibn Ibrahim said to this meaning¹³

Meaning:
Hoarding knowledge will throw you off the memory lane,
Then you will be viewed as ignorant and fool. 
You will be cast into hell fire in the day of resurrection.
And you would be burning with severest of punishment,

Imam Ali was reported to have said: Good is not increase in wealth or children but good thing is increase in knolwdege¹⁴
While line 14 described the peak of inner feelings and joy Allah
bestows on the knowledge ones. Muhammad Ibn Al-hassan
said:
... من وجد لذة العلم والعمل به قلما يرغب فيما عند الناس¹⁵
Meaning:
"Whoever tastes the sweetness inherent in practice (knowledge) would not be concerned with what others possess." The poet unburdens his mind by telling his reader from line 15-18 that he would have preferred leaving and working hard to being over whelmed or seduced by the material vanities of his world.

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13. Al-Imam Burha'nu -1-Islam Al-Zarnuji: Ta' Limulmatahalim fi Tariki ta' lumu 1970/ Daru ihya'hi- kutubi-I- Arabiya. P.34
14. Adam Abdullah A-Illori: At- Dinu Al-Nasihah 1999, Islamic cultural printing press, Agege p.14
15. Al-Imam Burha'nu-l- Islam Al-Zarnuji: Talim-l-muta' lim Tarika-l-muta'lim 1970/ Daru ihya'hi-1- kutubi -1- Arabiyah.P.9