Tricks in marriages

Narrated 'Abdullah:

Nafi narrated to me that 'Abdullah said that Allah's Apostle 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."

حَدَّثَنَا قُتَيْبَةُ بْنُ سَعِيدٍ، حَدَّثَنَا لَيْثٌ، عَنِ ابْنِ شِهَابٍ، عَنْ عُبَيْدِ اللَّهِ بْنِ عَبْدِ اللَّهِ بْنِ عُتْبَةَ، عَنِ ابْنِ عَبَّاسٍ، أَنَّهُ قَالَ اسْتَفْتَى سَعْدُ بْنُ عُبَادَةَ الأَنْصَارِيُّ رَسُولَ اللَّهِ ﷺ فِي نَذْرٍ كَانَ عَلَى أُمِّهِ، تُوُفِّيَتْ قَبْلَ أَنْ تَقْضِيَهُ، فَقَالَ رَسُولُ اللَّهِ ﷺ " اقْضِهِ عَنْهَا ". وَقَالَ بَعْضُ النَّاسِ إِذَا بَلَغَتِ الإِبِلُ عِشْرِينَ، فَفِيهَا أَرْبَعُ شِيَاهٍ، فَإِنْ وَهَبَهَا قَبْلَ الْحَوْلِ أَوْ بَاعَهَا، فِرَارًا وَاحْتِيَالاً لإِسْقَاطِ الزَّكَاةِ، فَلاَ شَىْءَ عَلَيْهِ، وَكَذَلِكَ إِنْ أَتْلَفَهَا فَمَاتَ، فَلاَ شَىْءَ فِي مَالِهِ.