Adam Clarke on Colossians 3:9

Lie not one to another - Do not deceive each other; speak the truth in all your dealings; do not say, "My goods are so and so," when you know them to be otherwise; do not undervalue the goods of your neighbor, when your conscience tells you that you are not speaking the truth. It is naught, it is naught, saith the buyer; but afterwards he boasteth; i.e. he underrates his neighbour's property till he gets him persuaded to part with it for less than its worth; and when he has thus got it, he boasts what a good bargain he has made. Such a knave speaks not truth with his neighbor.

Ye have put off the old man - See the notes on Rom 6:6; and particularly on Rom 13:11-14 (note). Ye have received a religion widely different from that ye had before; act according to its principles.