عَنِ ابْنِ عَبَّاسٍ رَضِيَ اَللَّهُ عَنْهُمَا;
أَنَّ اَلنَّبِيَّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ قَالَ: «لَوْ يُعْطَى اَلنَّاسُ بِدَعْوَاهُمْ، لَادَّعَى نَاسٌ دِمَاءَ رِجَالٍ، وَأَمْوَالَهُمْ، وَلَكِنِ اَلْيَمِينُ عَلَى اَلْمُدَّعَى عَلَيْهِ»
The Prophet (sallallahu alayhi wa sallam) said: “If people were given whatever they claimed (in disputes), some people would claim the lives and wealth of others; but the oath (of denial) must be taken by the defendant.”. al-Baihaqi has reported with a Sahih (authentic) chain of narrators: “But the proof (Bayyinah) lies on the one who is making the claim, and the other (Yamin) must be taken by the one who rejects the claim.”
Bulugh al-Maram 1605, Book 14, Judgments, Hadith 27. 1 min read