גיטין פד.
"ה"ז גיטך ע"מ שתאכלי בשר חזיר"
The Gemara says if a man gave his wife a גט on the condition that she goes up to the heavens, or on condition that she descends to the תהום, or that she crosses the ים הגדול by foot, ר"י בן תימא says this is a valid גט. He says a כלל: any condition that is impossible to fulfill but was stipulated in the beginning, we say that that the husband was only trying to annoy his wife, so the condition is בטל and the גט is כשר. The Gemara asks: if a man said this is your גט on the condition you eat בשר חזיר, what is the דין? Abaye says this is what ר"י בן תימא was referring to and since it is אסור to eat חזיר the תנאי is בטל and the גט is כשר. Rava holds since it is possible to eat the חזיר (although she will get מלקות), it does not fall into the כלל of ר"י, and the תנאי is binding. [ד"ה על] תוס' brings the Gemara that says if the תנאי of ascending to heaven is מקויים, the גט is כשר, if not it’s not כשר. Tosfos asks, how is it possible to ascend to heaven? Tosfos answers "על ידי שם". רע"א in גליון הש"ס says - עיין תוס' חגיגה י"ד - the Gemara says 4 people were"נכנס לפרדס" (Gan Eden) alive: בן עזאי, בן זומא, אחר, ר"ע. Tosfos there says that they used the "שם" to accomplish this and explains that לא עלו ממש, but rather by saying the שם, it appeared to them (spiritually) as if they had entered גן עדן. It seems that רע"א is asking that how can Tosfos by us say that theשם actually can get you into שמים?
The [אבה"ע ס' לח] שו"ע says if one is מקדש a lady with a תנאי that there be no חיוב עונה on him, the condition is בטל because it is considered being "מתנה על מה שכתב בתורה". The בית שמואל says that this is different than our Gemara where we say if one is מגרש his wife with a תנאי that she eats חזיר, here we don’t say this is a problem of מתנה על מה שכתב בתורה. He explains, the difference is by קידושין the husband is trying to create a חלות קידושין with a condition that is against the Torah. This is called מתנה על מה שכתב בתורה. In our case of Gittin, he is giving the גט with a condition, but she does not have to fulfill the condition, she could remain married, so in this case he is not making a חלות and therefore is not considered being מתנה על מה שכתב בתורה. [פסחים מד] חשוקי חמד was asked of there is anything wrong with creating and eating kosher imitationחזיר (bacon)? He brings the חיד"א that addresses, what if someone thought of חזיר while eating the מן, was he oiver an issur? He answers that since you know you are eating kosher it would be ok. Furthermore, we see that the wife of ר' יוחנן wanted to experience the taste of בשר בחלב so ר"נ gave her a roasted cow’s utter. So we see as long as you know that what you are eating is kosher, it is permitted. ר' זילברשטיין says he asked his father in law, ר' אלישיב, who said that if it is something that Hashem created, then it is ok to eat, but to create something from scratch just to experience the taste of חזיר, better not to do it.