פרשת קדושים תשי"ד - לא תגנבו ולא תכחשו ולא תשקרו...

לא תגנבו YE SHALL NOT STEAL — This is a warning addressed to him who steals money (the property of his fellow-man), but the law “Thou shalt not steal" which is contained in the Ten Commandments is a warning addressed to him who steals a human being. For this it what is learnt from the context, because it must be a matter for which one becomes liable to death by sentence of the court, (since the preceding laws in the Ten Commandments are of this character, which is the case with kidnapping and not with theft of money; cf. Rashi on Exodus 19:14) (Mekhilta 20:13:3; Sanhedrin 86a).

ולא תכחשו NEITHER SHALL YE DEAL FALSELY [WITH ONE ANOTHER] — Since Scripture has stated (Leviticus 5:21, 22) "[If a man sin… and deny unto his neighbour a charge, or a deposit… or has found that which was lost] and denieth it (וכחש בה)", that he shall pay the principal and add a fifth part more thereto, we have there mention only of the punishment he incurs; whence do we derive the prohibition (i.e. where is it forbidden)? From Scripture's statement here “neither shall ye deal falsely" (The Hebrew here is תכחשו, the same term as is used in the verse quoted — וכחש בה) (Sifra, Kedoshim, Section 2 3; Bava Kamma 105b).

If any one sin, and commit a trespass against the LORD, and deal falsely with his neighbour in a matter of deposit, or of pledge, or of robbery, or have oppressed his neighbour;

And he said unto him: ‘I also am a prophet as thou art; and an angel spoke unto me by the word of the LORD, saying: Bring him back with thee into thy house, that he may eat bread and drink water.’—He lied unto him.—

לא תגנבו YE SHALL NOT STEAL — This is a warning addressed to him who steals money (the property of his fellow-man), but the law “Thou shalt not steal" which is contained in the Ten Commandments is a warning addressed to him who steals a human being. For this it what is learnt from the context, because it must be a matter for which one becomes liable to death by sentence of the court, (since the preceding laws in the Ten Commandments are of this character, which is the case with kidnapping and not with theft of money; cf. Rashi on Exodus 19:14) (Mekhilta 20:13:3; Sanhedrin 86a).

And ye shall not swear by My name falsely, so that thou profane the name of thy God: I am the LORD.

לא תגנבו ולא תכחשו ולא תשקרו ולא תשבעו YE SHALL NOT STEAL, NEITHER DEAL FALSELY, NEITHER LIE, NEITHER SWEAR [ONE TO ANOTHER] - If you steal you will in the end come to deny it, then you will lie (in order to back up your first denial), and ultimately you will swear falsely (Sifra, Kedoshim, Section 2 5).