To answer your question "Abundance" is spoken of in the same context of "spirituality" in that PDF you sent it is spoken of on pages, 174, 182, 412, 585, 694, and 720.
or you can simply search "abundance"

For example from page 693/4

"If one is ill he ought to deal with every cause of his illness before the Lord. If, after all has been dealt with, the hand of God still remains upon him, then he should understand that this illness is for the purpose of restraining him from being proud or loose or for some other purpose. He should accept it and learn its lesson. To be sick is valueless if the lesson is not learned. Sickness itself does not make a
man holy, but its lesson if accepted produces holiness. Some grow worse spiritually during illness; they become more self-centered. That is why one must discover the lesson in such a period. What profit or fruit can be derived from it? Is the hand of God upon me to keep me humble as He did with Paul, “to keep me from being too elated by the abundance of revelations” (2 Cor. 12.7) ? Or is it because God desires to weaken my stubborn individuality? What is the use of sickness if it does not provoke me to learn the lesson of weakness? Many are sick in vain because they never accept the Lord’s dealing with their particular problems."