Gen 4:8 And Cain talked with Abel his brother: and it came to pass, when they were in the field, that Cain rose up against Abel his brother, and slew him.
See here, the fearful growth of the evil feeling in Cain's heart. It was only a thought at first but it was admitted into the heart and cherished there. Then it grew until it caused a terrible crime! We learn here, the danger of cherishing even the smallest beginning of bitterness; we do not know to what it will grow!
Some people think lightly of bad temper, laughing at it as a mere harmless weakness; but it is a perilous mood to indulge, and we do not know to what it may lead.
Sin is crouching at your door; it desires to have you! In His reproof of Cain, the Lord likens his sin to a wild beast lying in hiding by his door, ready to leap on him and devour him. This is true of all sin which is cherished in the heart. It may long lie quiet and seem harmless but it is only a wild beast sleeping!
There is a story of a man who took a young tiger and resolved to make a pet of it. It moved about his house like a kitten and grew up fond and gentle. For a long time its savage, blood-thirsty nature seemed changed into gentleness, and the creature was quiet and harmless.
But one day the man was playing with his 'pet', when by accident his hand was scratched and the beast tasted blood. That one taste, aroused all the fierce tiger nature, and the ferocious animal flew on his master and tore him to pieces!
So it is, with the passions and lusts of the old nature, which are only petted and tamed and allowed to reside in the heart. They will crouch at the door in treacherous lurking, and in some unguarded hour they will rise up in all their old ferocity!
It is never safe to make pets of tigers!
It is never safe to make pets of little sins!
We never know what sin may grow into if we let it abide in our heart!
Cain attacked his brother Abel and killed him! That is what came of the passion of envy in Cain's heart! It was left unrebuked, unrepented of, uncrushed — and in time it grew to fearful strength. Then in an evil moment, its tiger nature asserted itself!
We never know to what dreadful stature — a little sin may grow!
~J. R. Miller~