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).”  

نَهَى رَسُولُ اللَّهِ ﷺ عَنِ الشِّغَارِ وَالشِّغَارُ أَنْ يَقُولَ الرَّجُلُ لِلرَّجُلِ زَوِّجْنِي ابْنَتَكَ أَوْ أُخْتَكَ عَلَى أَنْ أُزَوِّجَكَ ابْنَتِي أَوْ أُخْتِي وَلَيْسَ بَيْنَهُمَا صَدَاقٌ  

[Machine] The Messenger of Allah ﷺ forbade equal treatment in marriage. He said, "Equal treatment is when a man says, 'Marry your daughter to me, and I will marry my daughter to you.' Or 'Marry your sister to me, and I will marry my sister to you.'" He also forbade the transaction of al-gharar (uncertainty) and al-hasah (the sale of stones used for weights).  

نَهَى رَسُولُ اللهِ ﷺ عَنِ الشِّغَارِ قَالَ وَالشِّغَارُ أَنْ يَقُولَ الرَّجُلُ زَوِّجْنِي ابْنَتَكَ وَأُزَوِّجُكَ ابْنَتِي أَوْ زَوِّجْنِي أُخْتَكَ وَأُزَوِّجُكَ أُخْتِي قَالَ وَنَهَى عَنْ بَيْعِ الْغَرَرِ وَعَنِ الْحَصَاةِ  

[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