Sustenance

Soudabeh:
Let's go back to the begining of the prayer, the person needs sustenance in order to do the act. If he doesn't have this sustenance, he has no power for doing  both material and spiritual act. 

اللهم قنعنی بما رزقتنی،
That is,it would be a sustenance  which is wide  and sufficient.  In material matters,  sustenance means what is in person's dignity and no more and it is also important in spiritual matters that he doesn't get much of things sooner than his time.
A lot of problems come back to this issue.  Sustenance must definitely lead the person to the act.  Sustenance certainly has a metabolism and leads a person to the act. In matters of spirituality,  we must consider multiplicity and plurality that it can cover.
(استرنی و عافنی)  
Ster is not just a preserver  but it is a cover for growth. Covering is  necessary to grow. 
A flower which is sensitive to cold, keep it from cold to grow. Ster( covering)  itself is the creation of the necessary bed for growth.  We make a greenhouse and put it in the shield to grow.