HETERIM FOR FLATTERY
(R. Yehudah bar Ma'arava): One may flatter the wicked in this world - "(in the world to come) a base person will not be called generous, the drunkard will not be called 'master'."
Inference: This is permitted in this world.
(Reish Lakish): We learn this from Yakov, who told Esav "(seeing you) is like seeing the countenance of Elokim, and I found favor with you."
This is unlike R. Levi. i. (R. Levi): What Yakov told Esav is like a man who sensed that his host wants to kill him. He told his host 'this food tastes like what I ate by the king. The host thought that the king knows the guest, and he was afraid to kill him.
Avodah Zarah 6b: On the day of his festival, a Min (idolater) sent newly minted coins to R. Yehudah Nesi'ah.
R. Yehudah Nesi'ah: If I accept them, he will thank his idolatry. If I do not accept them, he will bear enmity!
Reish Lakish: Throw them in a pit when he is watching. Make it look like it was accidental, so there will not be enmity.
26a (Mishnah): A Bas Yisrael may not help a Nochris give birth, for the child will serve idolatry. A Bas Yisrael may not nurse a Nochris' baby.
Contradiction (Beraisa): A Bas Yisrael may help a Nochris give birth for pay, but not for free. (Surely, one may not help deliver an idolater, even for pay!)
Answer (Rav Yosef): It is permitted for pay, to avoid enmity.
(Rav Yosef): To avoid enmity, a Bas Yisrael may, for pay, help a Nochris give birth on Shabbos, or nurse a Nochri baby.
Rejection (Abaye): She can avoid enmity. She can say 'we may desecrate Shabbos only for a baby that will observe Shabbos.' Nursing will inhibit marriage (if she is single), or (if she is married) it will make her husband despise her!'
(Beraisa): We do not throw into a pit (overtly kill) shepherds (who graze their flock on others' property) or Nochrim, nor may we save them from a pit.
(Rav Yosef): One may save them for pay, to avoid enmity.
Rejection (Abaye): He can avoid enmity by saying 'now, my son is in danger on the roof', or 'I must meet the officer now, or else I will suffer a great loss.'
Yevamos 65b (R. Ilai): One may deviate (from truth) for the sake of Shalom - "your father commanded ... tell Yosef to bear the sin (of his brothers)".
(R. Noson): This is a Mitzvah - "and Shmuel said ... Sha'ul will hear (that I am going to anoint David) and he will kill me" (so Hash-m told him to lie).
Nedarim 22a: Two people from Bei Chuzai accompanied Ula when he came to Eretz Yisrael. One slaughtered the other, and asked Ula if this was proper.
Ula: Yes! Open his neck (so he will die quickly)!
Question (Ula): Did I sin by condoning a sinner?
Answer (R. Yochanan): No, you saved your life!
The Rif and Rosh (Yevamos 21 and 6:21) bring the Gemara in Yevamos.
Rosh (Avodah Zarah 1:1 Sof 6a): Why is the custom to permit business with Nochrim, or loans to or from them on the day of their festival (unlike the Mishnah)? The Rashbam cited Rashi (Teshuvas Rashi 327) to say that Nochrim nowadays are not true idolaters. They do not thank their idolatry for such things. Nochrim in Chutz la'Aretz are not real idolaters, they merely keep their parents' customs (Chulin 13b). Also, our main income throughout the year is from Nochrim. If we would refrain on the day of their festival, there would be enmity. Had R. Yehudah Nesi'ah not found a better solution, he would have accepted the Min's gift to avoid enmity, even though the Min would have thanked his idolatry. To avoid enmity, Rav Yosef permitted helping a Nochris give birth on Shabbos, nursing a Nochri baby, and raising a Nochri who fell into a pit. Abaye disagreed only because one can avoid enmity. The Yerushalmi (2b) permits business with a Nochri he knows, for this is like flattery. Similarly, if one enters a city and finds them rejoicing on their festival, he may rejoice with them, for this is like flattery.
Ran (Avodah Zarah 1b DH Dinra): One may do business with a Nochri who knows him, for this is like flattery. A Ba'al Nefesh should minimize this. Whenever we can evade him, it is forbidden.
Tosfos (41b DH Kol): Flattery is permitted when there is danger. R. Yochanan told Ula that he acted properly to save his life (Nedarim 22a).
Orchos Tzadikim (Sha'ar ha'Chanufah DH ha'Teshi'i): The Heter to flatter Resha'im is only due to fear lest he harm him. This permits honoring a Rasha the way people honor strong people. He may not praise him in front of people. Some Resha'im we do not flatter. They told Mordechai to flatter Haman, and he answered "do not seek their Shalom or wellbeing." One may flatter his wife for Shalom Bayis, his creditor lest he pressure him, his Rebbi so he will teach him. It is a big Mitzvah to flatter one's Talmidim and friends, so they will learn from him and accept his rebuke.
Shulchan Aruch (YD 148:12): Some say that the Isur to do business with Nochrim or lend to them on the day of their festival does not apply nowadays, for they are not so proficient about idolatry.
Rema: Further, there is enmity if we separate from them on their festival, and we dwell among them and need to do business with them the entire year. Therefore, if one enters a city and finds them rejoicing on their festival, he may rejoice with them, for this is like flattery. However, a Ba'al Nefesh should avoid this if possible without enmity.
Terumas ha'Deshen (195, cited in Terumas ha'Deshen): If one must send to a Nochri on their new year, he should send before dark on the day before. If the day before is Shabbos, he sends on the new year, for the Nochri is adamant not to receive it later or much earlier.
Mishnah Berurah (156:4): One must refrain from flattery. The Magen Avraham permits deviating (from one's true feelings) for the sake of Shalom, but he cites Sefer Chasidim (who permits this only for matters of the past). This requires investigation.
Pischei Teshuvah (YD 334:19, citing Bechor Shor (Sotah 46b)): Many learn from our Gemara that one may flatter anyone close in any way to authorities, even if there is no clear danger. This is wrong! Mahariyo (157) was lenient only when there is clear danger. Surely, Lo Saguru (the Isur to fear litigants) was said when there is reason to fear!