Not only did God say that he had been robbed in tithes, but also in offerings. I certainly don't want the Lord to consider me a robber by failing to give tithes and offerings. An offering is what we give over and beyond your ten percent tithe. Now you have the freedom to graciously give as you are directed by the Spirit of God through your place of worship and fellowship, ministries or to the ministers of God (man or woman).
The Lord gave us a wonderful tale about Cain and Abel regarding their OFFERINGS to the Lord. According to the Holy Bible the Lord accepted one of the OFFERINGS and rejected the other through grace.
"But Abel brought fat portions from some of the first born of his flock. The Lord looked with favor on Abel and his offerings, but on Cain and his offering he did not look with favor. So Cain was very angry, and his face was downcast.” Genesis 4: 4-5.
Certainly, there is an important lesson for us to learn here. Another similar example was when God asked Abraham to offer Isaac to him, but it is more about trusting God. Genesis 22:1-14