Two Ways to Overturn
The longest haftara of the year is the one we read at Mincha on Yom Kippur an entire sefer from the Trei Assar collection of twelve minor prophecies. The entire dramatic account revolves around the mission which G-d gave to the Prophet Yonah regarding the sinful Assyrian Empire. After an unsuccessful attempt to evade his mission and a sojourn in the belly of a whale, Yonah finally reached the capital city of Nineveh and announced in the name of G-d that "in another forty days Nineveh will be overturned" (Yonah 3:4).
This statement, it turns out from our gemara, was a double entendre, a twofold prediction of which the prophet understood only one meaning.
A disciples of Rabbi Chisda stated in the presence of his teacher that a prophet who withholds his prophecy and fails to communicate it to its intended audience is liable for lashes. Rabbi Chisda challenged him that there could be no witnesses to such withholding to issue him the warning, which is a prerequisite for any corporal or capital punishment. To this the Sage Abaye responded that his fellow prophets would be aware of the prophecy and could warn him against withholding. Their awareness of the prophecy of others is found in the words of the Prophet Amos who declared that "G-d will not do anything without first revealing it to His servants, the prophets" (Amos 3:7).
The challenges, however, continued. Perhaps the decree contained in prophecy received by that prophet was subsequently annulled by the heavenly host? If that were so, came the answer, G-d would have informed the other prophets of this as well. At this point the experience of Yonah is cited. The decree to overturn Nineveh was annulled, as we read at the end of the haftara, and Yonah was not informed in advance!
Yonah, it is finally explained, never received a prophecy of destruction to require informing him when the decree was annulled. He was told that Nineveh would be "overturned" which could also mean that the people of that city would "turn over" their behavior and repent. It was Yonah who mistakenly interpreted it as an absolute prophecy of destruction and the events finally set him straight without the need for a prophecy of rectification.
Disowning the Underserving
Avraham had three sets of children Yitzchak from his wife Sarah, Yishmael from his servant Hagar, and six sons from his concubine Keturah. Before his passing he bequeathed his entire fortune to Yitzchak and gave the others some gifts (Bereishet 25:5-6).
This bit of history was cited by the Sage Gaviha ben Pasisa before the court of Alexander of Macedon to refute the claim made to a share of Eretz Yisrael on the basis of being heirs to the patriarch to whom the land was given. In his triumphant argument he pointed out that just as a father has a right to divide up his estate during his lifetime as he sees fit, so did Avraham bequeath Eretz Yisrael to Yitzchak and his descendants only.
But, asks Rabbi Eliyahu Mizrachi in his commentary on Chumash, why did Avraham, who fulfilled all the mitzvot, ignore what our Sages say (Mesechta Ketubot 53) about the impropriety of disowning one son in favor of the other even when one is good and the other evil (because one can never know what good descendants will come from the evil son)? His own answer to this is that Avraham understood from G-ds statement to him when Sarah asked him to banish Yishmael from their home, that "your seed will be called those of Yitzchak" (Bereishet 21:12), that it was a Divine directive to disown the others.
Maharsha, however, takes a different approach. A child born of a female servant is not considered the child of his father and has no right of inheritance. The children of Keturah were indeed born after she was freed and permitted in marriage but their status as the offspring of a concubine did not entitle them to the equality mentioned by the aforementioned gemara.
This insight of the Maharsha helps explain a gemara in Mesechta Kiddushin (68a) which bases the rule that that a union between a Jew and a Canaaite servant woman cannot constitute a halachic marriage on the statement which Avraham made to Eliezer and Yishmael as he approached Mount Moriah to sacrifice Yitzchak. "Sit here with the donkey," he told them, thus equating them with an animal which has no institution of marriage. While this is generally assumed to be a reference to Eliezer who was indeed a slave, the plural term used by Avraham indicates that it included Yishmael as well.