Sayyiduna Ibn Umar (may Allah be pleased with them both) said: The Messenger of Allah (peace and blessings be upon him) forbade shighar. Imam Malik (may Allah have mercy on him) said: And shighar is that a person marries off his daughter or sister on the condition that the other person also marries off his daughter or sister to him without a dowry. Imam Darimi (may Allah have mercy on him) was asked: Will such a marriage be valid? He replied: I do not like it.
Hadith Referenceسنن دارمي / من كتاب النكاح / 2217
Hadith Gradingتحقیق (حسین سلیم أسد الدارانی):إسناده قوي وهو عند مالك في النكاح، [مكتبه الشامله نمبر: 2226]
Hadith Takhrijاس روایت کی سند صحیح اور حدیث متفق علیہ ہے۔ دیکھئے: [بخاري 5112] ، [مسلم 1415] ، [أبوداؤد 2074] ، [ترمذي 1124] ، [نسائي 3337] ، [ابن ماجه 1883] ، [أبويعلی 5795] ، [ابن حبان 4152]
Brief Explanation
(Commentary on Hadith 2216)
The definition of shighar has already been mentioned above from Imam Malik rahimahullah: it is a marriage of exchange without a dowry (mahr), such that I marry your sister or daughter on the condition that you also marry your sister or daughter to me without a dowry. Such a marriage is unanimously forbidden by the scholars. However, there is a difference of opinion as to whether the marriage contract itself is valid or not.
The majority of scholars declare it invalid (batil).
Imam Abu Hanifah rahimahullah said: The marriage will be valid, and each party will be required to pay the customary dowry (mahr mithl).