"Cain brought to the Lord an offering of the fruit of the ground and Abel brought of the firstborn of his flock and of the fat portions. And the Lord had regard for Abel and his offering, but for Cain and his offering He had no regard." (Genesis 4:3-5 ESV)
It's all in the details...Cain only gave God something he has while Abel offers the best he has--the firstborn and fat portions were valued possessions. Something I notice is that it doesn't mention the amount of the offering--just the quality. God sees the value we place on our worship and He responds.
And here is the challenge...Do I give my best to God in worship?
Too many times I find myself giving God less than my best. Sometimes, all I offer are my "leftovers"--my leftover time, leftover thoughts or leftover resources.
When will I learn that God doesn't like leftovers? I want God to "regard" my offering and never waste His time or mine.