EDIT "and through man"....pastors (MAN) are keeping themselves in business by saying this.
The Cain/Abel story wasn't encouraging us to give according to OUR decisions/will, it was about giving according to THE LORD'S WILL. Cain and Abel were both informed about what the proper offering should be. Cain's offering was not accepted because Cain did not obey The Lord's will. Cain decided to do what what his heart/mind told him that he should do (COMPLETELY DISREGARDING The Lord's will).
....do you need to be commanded/ordered to do "good"?......many believers are convinced that they need to be ordered to do what is right (yes, the god of confusion has convinced all of humanity that we can't help being scoundrels/garbage, criminals, etc., don't fall for that lie).
Modern worshipers also disregard God's "WILL" for the sake of obedience to the bible, and "COMMANDS", and "pastors", and THEIR "INTERPRETATIONS", and "INTELLECT" of their heart and mind (do you mistrust what The Lord says and think He "MEANS" different than He says?).
Scripture is FILLED with what was said long ago to JEWS, pagans, and uncivilized people that had slaves and idols of superstition. We have to use our common sense (spiritual common sense, 1 John 2:27) to realize what is good Godly sentiment/spirit and devotional practice for today.
It is The Lord's WILL that we should be concerned about ABOVE ALL printed matter and also above what WE think is right (OUR WILL misguides us).....God will show us the error of OUR way/will IF we decide to be good LISTENERS instead of resent and fear His instruction (but most believers want to FEAR His reproach). Most believers have decided to do the same as CAIN.
So, don't do what is in your heart like Cain did. God's WILL is that you TRUST HIM. HE DID ALL THE "WORKS" NECESSARY for your SALVATION (John 6:28) and your only obligation is to TRUST that those "works" are sufficient for your salvation (let His works be 'manifested' in your life......be confident in Jesus, relaxed in Jesus, and REST IN JESUS).
The Israelites didn't have God's rest. In their lifetime, they never entered God's "REST"....
Hebrews 4:3
"They shall never enter my rest".
....but WE do have REST IN JESUS.
The human "heart" is a 'wishy washy bleeding heart', do not be misguided by doing what your HEART tells you to do....
"But be TRANSFORMED by the renewal of THE MIND" (Romans 12:2).
...AMEN?...The Lord knows exactly what we need to understand, and it's all there in scripture IF we look for HIS WILL, not the COMMANDS, HIS "WILL"/desires....
....(Godliness is not an 'obedience contest', or an 'intelligence contest', or a 'scripture memorization' contest, or a 'doctrine knowledge' contest, it is a 'love/trust God and His WILL' contest).
.....("faith FOR FAITH", Romans 1:17, no more simple faith "TOWARD" God like Cain did, Hebrews 6:1).
JESUS is our ONLY foundation for salvation, NOT the bible, pastors, "repentance", or doctrine skills, etc.
Now that we already know the "doctrine of Christ" (gospel of Jesus's 'sin sacrifice'), we should move on to having a better, deeper devotion based on love/trust for God (God only, "For God is not so unjust....", read Hebrews chapter 6 carefully).....a LOVE 'RELATIONSHIP' devotion so that OUR LIFE becomes our "PRAYER".
God tells us that "The heart is evil continuously" (always misleading).
How many tears of love ("living water", John 7:38) can you shed for Him? Do you also love HIS WAYS of peace, truth, and justice?