The Messenger of Allah ﷺ forbade shighar.I asked Nafi, "What is shighar?"He replied, "It is when a man gives his daughter in marriage to another man on the condition that the other man gives him his own daughter in marriage, or when a man gives his sister in marriage to another in exchange for the other's sister, with no dowry paid in either case."
حدثنا يحيى عن عبيد الله عن نافع
أن رسول الله ﷺ نهى عن الشغار قال قلت لنافع ما الشغار قال يزوج الرجل ابنته ويتزوج ابنته ويزوج الرجل أخته ويتزوج أخته بغير صداق