Sahih al-Bukhari 6960
صحيح البخاري#6960SahihNarrated 'Abdullah: Nafi narrated to me that 'Abdullah said that Allah's Messenger (ﷺ) forbade the Shighar. I asked Nafi', "What is the Shighar?" He said, "It is to marry the daughter of a man and marry one's daughter to that man (at the same time) without Mahr (in both cases); or to marry the sister of a man and marry one's own sister to that man without Mahr." Some people said, "If one, by a trick, marries on the basis of Shighar, the marriage is valid but its condition is illegal." The same scholar said regarding Al-Mut'a, "The marriage is invalid and its condition is illegal." Some others said, "The Mut'a and the Shighar are permissible but the condition is illegal
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Every narration in Sahih al-Bukhari is accepted as Sahih (authentic) by the established status of the book.
In-book reference: 90:7