No Leaven!

2.11  "No meat offering, which ye shall bring unto the Lord, shall be made with leaven..."

Leaven - (Websters) something that modifies such as yeast to make 'sour' dough.
Why couldn't leaven be added to the "meat/meal" offering?  If a "modifier" is used, then the offering is not "of the Lord" but "modified and made "sour" by the leaven.  

It is clear that God that God wants me - ALL of me - just as He designed, after grace through faith."  Any "offering" presented with an attitude of "look what I've done for the Lord," makes that offering "sour" and displeasing to HIM, thus is rejected.

Genesis 4:3-7

• Abel gave the firstlings of the flock.  That is, he gave humbly of the Lord's provision.
• Cain gave also of the Lord's provision but gave a thing, pridefully "modified" or grown by his own hand, thus was rejected.
• The key is attitude.  Real offerings originate from HIM and humbly presented back to HIM.

 Any blessing(s) such as possessions, talent or time are His "from whom all blessings flow," to be used as He sees fit.