Sayyiduna Abdullah bin Umar (may Allah be pleased with him) says that the Prophet (peace and blessings be upon him) said: "Do not sell over one another's sale." In the narration of Abu Zakariyya it is: "He should not sell."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب البيوع / 10888
Sayyiduna Abdullah bin Umar (may Allah be pleased with him) says that the Messenger of Allah (peace and blessings be upon him) said: "None of you should sell over the sale of his brother, nor should he send a marriage proposal over the proposal of his brother, except with his permission."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب البيوع / 10889
It is narrated from Sayyiduna Abu Hurayrah (may Allah be pleased with him) that he (peace and blessings be upon him) said: "Do not inflate prices (by fake bidding), a town-dweller should not sell for a desert-dweller, a man should not sell over the sale of his brother, nor should he propose over his proposal, and a woman should not ask for her sister's divorce so as to empty what is in her vessel."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب البيوع / 10890
Sufyan mentions it in the same way with his chain, except that he said he traced it back to the Prophet (peace and blessings be upon him), and it has the addition: "A man should not bargain over the bargain of his brother."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب البيوع / 10891
Sayyiduna Abu Hurayrah (may Allah be pleased with him) says that the Messenger of Allah (peace and blessings be upon him) said: "Do not sell over one another's sale."
Imam al-Shafi'i (may Allah have mercy on him) says: A man bought goods, and the two had not yet separated when another man came and offered him goods like it, or better than it, for a lower price, so he cancels his companion's sale, since he has the option before they separate. This is corruption, and he has disobeyed Allah if he knew the hadith, and the sale will be binding.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب البيوع / 10892