The Prophet ﷺ forbade that a town dweller sell on behalf of a desert dweller, or that people artificially inflate prices, or that a man propose to a woman already engaged to his brother, or that he attempt to sell over the sale of his brother. A woman must not request the divorce of her sister so as to empty what is in her bowl or her vessel. Let her marry, for her provision rests with Allah.
حدثنا سفيان حدثنا الزهري عن سعيد بن المسيب
أن النبي ﷺ نهى أن يبيع حاضر لباد أو يتناجشوا أو يخطب الرجل على خطبة أخيه أو يبيع على بيع أخيه ولا تسأل المرأة طلاق أختها لتكتفئ ما في صحفتها أو إنائها ولتنكح فإنما رزقها على الله
Its isnad is sahih. Bukhari related it, 4:295, from Ali bin Abdullah, who is Ibn Madini, and Muslim, 1:299, from Amr Naqid, Zuhayr bin Harb, and Ibn Abu Umar, all of them from Sufyan bin Uyayna, with this isnad. But in this narration of the two sheikhs, the ending is not included, from "and revives" to the end of the hadith. The two sheikhs related its meaning scattered across their chapters, through different routes. See Al-Muntaqa 2839, 2846, 3425, 3507. See also Fath al-Bari 4:312, 9:190–191. Part of its meaning has already appeared in the hadith of Abdullah bin Umar, 4722, and part of it in the hadith of Abdullah bin Amr bin As, 6647.As for his saying, "He forbade a town dweller to sell on behalf of a desert dweller," Ibn Athir said, the town dweller is one who resides in cities and villages, and the desert dweller is one who resides in the desert. What is forbidden is that the bedouin comes to the town with provisions, wishing to hasten selling them cheaply, and the town dweller says to him, "Leave it with me so I can raise its price in selling it." This practice is forbidden (muharram), because of the harm it causes to others. It has already appeared in the Musnad of Ibn Abbas, 3482, that Tawus said, "I said to Ibn Abbas, what does his saying, 'a town dweller on behalf of a desert dweller' mean?" He said, "He should not act as his broker."As for his saying, "Do not practice najsh," the meaning of najsh has already been explained at 4531.As for his saying, "so that she may empty what is in her bowl or her vessel," Ibn Athir said, this is the form "taftail" from "kafaat al-qidr," meaning she turned it upside down to empty out what was in it. It is said, "kafaat al-ina" and "akfaatuhu," meaning he turned it upside down, or meaning he tilted it. This is a figure of speech for the co-wife tilting toward herself the right that belongs to her companion from her husband, when she asks him for her companion's divorce. As for "sahfa," with a fatha on the sad and a sakin on the plain ha, Ibn Athir said, the sahfa is a vessel like a wide bowl or similar, and its plural is sihaf. This is a metaphor, meaning to monopolize for oneself what rightfully belongs to another, so that she becomes like one who empties out another's bowl and pours what is in her vessel into her own vessel.