The Word “Deshen” is taken form the Hebrew word translated “fatness” in the verse below
They shall be abundantly satisfied with the fatness of thy house; and thou shalt make them drink of the river of thy pleasures (Ps. 36:8 KJV).
It implies abundant, quality spiritual knowledge through teachings. God fills us with the knowledge of His Word to make us grow to the fullness of Christlikeness in us.