Preaching: Purity Not Jealousy

The very first story about murder in the Bible can be found in Genesis 4:1-10, a story of two brothers Cain and Able. When called by God to offer a sacrifice, Able offers the best of his crop while a conservative Cain keeps the best of his crop and offers little. Able sacrificed the best of his offerings with the faith that God’s will would prevail whilst Cain assumed being the elder of the brothers, any amount offered would suffice God’s request. After seeking favour with God, Able is then killed by Cain in an act of jealousy. Do we sacrifice whole heartedly just as Able did with pure hearted faith? or rather do we offer little yet expect favour with God as Cain did?