One of the very first commands God gave man was to give. Cain and Abel were asked to give a sacrifice to God, appropriate to His will. God, explaining to Cain why his offering was not acceptable, states in Genesis 4:7,
If you do well, will you not be accepted? And if you do not do well, sin lies at the door. And its desire is for you, but you should rule over it.
Giving an offering to God was not just a matter of convenience or the “thing to do,” giving was a serious action with serious consequences. If the giving was unacceptable, God explains, “sin lies at the door.”