[Machine] The Messenger of Allah ﷺ prohibited from reciprocal matchmaking. Reciprocal matchmaking means when a man says to another man, "Marry my daughter and I will marry your daughter. Marry my sister and I will marry your sister."
نَهَى رَسُولُ اللهِ ﷺ عَنِ الشِّغَارِ زَادَ ابْنُ نُمَيْرٍ وَالشِّغَارُ أَنْ يَقُولَ الرَّجُلُ لِلرَّجُلِ زَوِّجْنِي ابْنَتَكَ وَأُزَوِّجُكَ ابْنَتِي وَزَوِّجْنِي أُخْتَكَ وَأُزَوِّجُكَ أُخْتِي
Shighar means that a person should say to the other person: Give me the hand of your daughter in marriage and I will (in return) marry my daughter to you; or merry me your sister, and I will marry my sister to you.
نَهَى رَسُولُ اللَّهِ ﷺ عَنِ الشِّغَارِ زَادَ ابْنُ نُمَيْرٍ وَالشِّغَارُ أَنْ يَقُولَ الرَّجُلُ لِلرَّجُلِ زَوِّجْنِي ابْنَتَكَ وَأُزَوِّجُكَ ابْنَتِي أَوْ زَوِّجْنِي أُخْتَكَ وَأُزَوِّجُكَ أُخْتِي
Ibn Umar said: “The Messenger of Allah forbade Shighar. Shighar is when a man says to another man: 'Marry your daughter or sister to me, on condition that I will marry my daughter or sister to you,' and they do not give any dower (i.e. neither of them give other the dower).” (Using translation from Ibn Mājah 1883)
نَهَى رَسُولُ اللهِ ﷺ عَنِ الشِّغَارِ وَالشِّغَارُ أَنْ يَقُولَ الرَّجُلُ لِلرَّجُلِ زَوِّجْنِي ابْنَتَكَ وَأُزَوِّجُكَ ابْنَتِي أَوْ زَوِّجْنِي أُخْتَكَ وَأُزَوِّجُكَ أُخْتِي قَالَ وَنَهَى عَنْ بَيْعِ الْغَرَرِ وَعَنِ الْحَصَاةِ