Every tree that does not bear good fruit is cut down and thrown into the fire. Thus you will know them by their fruits. If you, Rahula, reflecting thus, should find it so, a deed of body like this, Rahula, is certainly not to be done by you. I warn you, as I warned you before, that those who do such things shall not inherit the kingdom of God. It is fear to God and good character.
Similar reflection is recommended with respect to deeds of speech and deeds of thought.
It should be done before, during, and subsequent to one's action so that the moral quality of the deed can be experientially tested in light of these criteria. The Pali term akusala, translated 'unskill,' is the principal ethical term used in the sense of immoral in the Theravada scriptures. James 3.13-18, p. 798. But what comes out of the mouth proceeds from the heart, and this defiles a man. For out of the heart come evil thoughts, murder, adultery, fornication, theft, false witness, slander.