Silsilat al-Ahadith al-Sahihah

Abdullah bin Umar (may Allah be pleased with them both) narrates that the Messenger of Allah (peace and blessings be upon him) forbade the townsman from selling on behalf of the villager, and he (peace be upon him) also said: "Do not go out to meet the traders (rather, let them reach the market); do not make a deal over the deal of another; and do not send a marriage proposal over the proposal of another, until the first suitor gives up (the idea of marrying that girl) or permits the other brother to send a proposal."