Why did Yonah not command circumcision on the people of Ninevah, especially in the light of the message of Teshuvah?

Question

Why did Yonah not command circumcision on the people of Ninevah, especially in the light of the message of Teshuvah?

Whether for the purpose of Teshuvah or not, Joseph did command circumcision on the people of Egypt (Rash"i on Bereshith 41:55)

Answer 1

The people of Ninveh weren't Jewish. They weren't obligated in circumcision, and thus circumcision wouldn't do anything for them, spiritually. Circumcision is not a component of repentance. (Well, except for a Jew who was obligated and has so far opted not to do it.) The citizens of Ninveh instead accomplish repentance following the time-honored formula: by giving back everything they had stolen, asking forgiveness of their victims, and then confessing, regretting, and committing to God to do better.

(See for instance Igros Moshe OC4:116, where Rabbi Feinstein states forcefully that inflicting physical pain on oneself is not part of the formula for repentance.)

The Midrash about Joseph telling the Egyptian populace to get circumcised says nothing about having them repent. (Repent from what? The verses there don't [yet] blame the Egyptians for anything; whereas the Ninveh-ites, like the generation of the flood, are explicitly guilty of chamas -- strong-armed theft.) The easiest way to read that Midrash is that Joseph is thinking ahead, trying to prevent the Egyptians from labeling the Jews as "inferior others"; if they are all circumcised, it's harder to make that case.

Answer 2

The Kli Yakar on that verse in Bereishit says that Yosef's action was done for a reason irrelevant to the people in Ninveh. According to the Kli Yakar (I'm summarizing from the text I found on sefaria.org), we find in the Torah text that the word for foreskin (orlah) is equated to the word cherpah (shame) and the word for famine (ra'av) is also equated with the word cherpah (in Ezekiel, 36:30). Therefore, one can remove the cherpah (famine) by removing the cherpah (foreskin) (in his words, "חשב שבהסרת חרפת הערלה יוסר מהם חרפת הרעב")

Since the issue with Ninveh was not related to famine, it would not have been relevant to make circumcision part of the process of repentance.

A second answer he gives relates to the specific bad behavior of the Egyptians in terms of their sexual practices, tying their famine to their immorality, so the removal of foreskin was a form of repentance specific to the sin which brought about the lack of food. As that is not relevant to the situation in Ninveh, the circumcision would not have been a pertinent form of repentance.