If this title caught your eye, I'm glad, since it can be proven from scripture that Abel was a prophet. Turn with me to Luke 11:49-51, where Christ makes it clear that Abel was as much a prophet as Zacharias was (cf. 2 Chron. 24:15-22). We read in Jude 14-15 that Enoch was a prophet, and that Noah was a preacher of righteousness (2 Pt. 2:4), but before either of these men were even born, Abel prophesied. To whom? Of what? I think that a close comparison of Gen. 4:1-8 with 2 Chron. 24:15-22 may provide some additional details, and due to the cyclical nature of the Bible ("that which is done is that which shall be done:" Eccl. 1:9), what happened to Zacharias may shed light on what happened to Abel.
Christ affirms in Mt. 23:35 that Abel was righteous, as does the writer of Hebrews (Heb. 11:4) and the apostle John (1 John 3:12). So, since in "the mouth of two or three witnesses shall very word be established" (2 Cor. 13:1), including the Lord's own mouth, we can rest assured that Abel was righteous.
Notice in Gen. 4:3 that a "process of time" precedes his last days. During this time the characters of Abel and his brother revealed in vv. 4-8 develop. Abel is a sincere worshipper of God, likely the meditative type like David after him, spending long hours alone with his sheep...and God. Abel is a keeper, whereas Cain is a tiller, a hard worker. Reminds me of the prodigal's brother: "Lo, these many years I serve thee" (Luke 15:29), and yet he despises his penitent brother, picturing the Pharisees' estimation of their penitent countrymen (Luke 15:1-2). These same Pharisees conspire to slay Christ, also typified by Abel (Heb. 11:4, 12:24).
At some point, probably more than once, Adam explained to his sons why they wore animal skins. The blood of animals, Adam said, was required to atone for our sins and restore our fellowship with God (Gen. 3:21). Abel obviously took that to heart and applied it in Gen. 4:4. I think that God "testif[ied] of his gifts" (Heb. 11:4) by sending fire from heaven to consume his offering, just as on mount Carmel he testified of Elijah's offering (1 Ki. 18:24, 38-39) and on other occasions (Gen. 15:17; Lev. 9:24; Judg. 6:21; 1 Chr. 21:26; 2 Chr. 7:1--for a total of seven times!). An alternate scenario is that the brothers went to the gate of the garden, kept by Cherubims, and the fire came from the flaming sword. I tend to think that it was the first scenario rather than the second.
When self-righteous Cain saw this, instead of fearing God and offering the proper sacrifice, which God graciously encourages him to do in 4:7, he boils in rage and determines to retain his self-righteousness no matter the cost (Job 27:5-6; Luke 7:29-30, 16:15). I know that Cain was self-righteous, rather than a seeker of God's righteousness like Abel, because when God tells him how to "do well" in v. 7, he ignores him (Rom. 10:3) and eliminates the one who reminds him that he's not, just as a certain nation did about 4000 years later (Eccl. 1:9!). Furthermore, God not only tells Cain how to be righteous before him ("accepted," v. 7), but also that sin does not have to rule him practically; rather, he can rule over it if he will obey God. So it is in all dispensations: sin did not dominate the lives of the righteous Zacharias and Elisabeth (Luke 1:6) under the law, nor did it dominate the lives of righteous Abel, Enoch, Noah, Abraham, and Job before the law, nor should it dominate our lives under grace (Rom. 6:12-15).
How does Cain rid himself of Abel? His conversation may have been a ploy to lead him Abel out into the field, away from the family and others who might hear (Cain was married by now--4:16). Or, he may have known where to find Abel in the field (Judas knew where to find Christ). Now, considering how his antitype Zacharias meets his end in 2 Chron. 24 (stoning), it's my assertion that this may have been the method Cain chose to slay his brother. Other prophets met their doom in this fashion (Acts 7:58; Heb. 11:37), and Cain may have led Abel to a place where he had "ammunition" waiting. Or, he may have grabbed Abel's rod and/or staff (Ps. 23:4), whatever he had, and slew him with that.
But something else happened, I believe, before Abel's martyrdom. Remember that what precipitated Zacharias' stoning was rebuking the apostate Judeans for their idolatry (wrong worship). I think that the prophet Abel may have spoken his last, and perhaps first, prophecy to his brother Cain, and that it was similar to, if not the same, as what God said to Cain in Gen. 4:7: if he would follow the light he had (v.7!), God would accept him, and it would go well with him practically; if not, sin would run him and he would end up in hell. Since Cain had rejected the light God gave him in v. 7, I don't think God gave him more light, but rather restated through Abel what Cain already knew, in hopes that he would repent.
That is more than self-righteous Cain, who is "of that wicked one," could stand, however, and he grabs a stone or Abel's own instruments and starts in on Abel. I wouldn't be surprised if Abel's last words are something like Zacharias' in 2 Chr. 24:22, "...The LORD look upon it and require it." I know that Christ and Stephen ask God to forgive their killers, but Abel precedes them dispensationally, and when he is dead, his blood cries out to God for vengeance (4:10), and vengeance Cain receives (vv. 11-12). He slays a prophet, and becomes a vagabond thereafter. Antitypes: (1) the Jews slay their prophets under the kingdom, and are scattered thereafter (2 Chr. 36:20; John 11:52; Acts 19:13); and (2) the Jews slay John Baptist, Christ, and Stephen, and are driven out of their land in 70 A.D. (Luke 21:20-24).
So ends the brief, but remarkable life of the prophet Abel. No doubt Cain is burning in hell right now (Jude 11, 13), and Abel's soul is comforted in the presence of the one he typified, the Lord Jesus Christ (Eph. 4:8-9). Prophets may suffer affliction (James 5:10), but their end is truly blessed (Acts 22:20; Rev. 2:10).