"Just as an artist cannot paint in empty air, so it is futile to begin vipassana practice without a basis in morality and understanding of the law of kamma. Without these two things, there will be no surface, as it were, to receive concentration and wisdom. In some meditation centers, morality and kamma are ignored. Not much can result from meditation under these circumstances."
Sayadaw U Pandita. "In This Very Life. The Liberation Teachings of the Buddha." Wisdom Publications, Boston, MA, 1992.