DEUT1238 Concerning thought, our Sages have already said in the beginning of our baraisa (Avodah Zarah 20b): "'You shall be careful of all evil things' [this verse], which means that a person should not think [lewd] thoughts by day which will [then] lead to his becoming impure at night." (Yoma 29a): "Thoughts of sinning are worse than the [actual] sin." This is stated explicitly (Mishlei 15:26): "Evil thoughts are the abomination of the Eternal."