The burden of proof lies with the one making the claim

Two women were stitching shoes in a house or a room. Then one of them came out with an awl driven into her hand, and she sued the other for it. The case was brought before Ibn ʿAbbās, Ibn ʿAbbaاs said: the Messenger of Allah ﷺ said, "If people were to be given what they claim ˹without the burden of proof˺ the life and property of the people would be lost." So remind her of Allah and recite before her: "Indeed, those who exchange the covenant of Allah... (Āl ʿImrān 3:77)" So they reminded her and she confessed. Ibn ʿAbbaاs then said: The Prophet ﷺ said, "The oath must be taken by the defendant."  

أَنَّ امْرَأَتَيْنِ كَانَتَا تَخْرِزَانِ فِي بَيْتٍ أَوْ فِي الْحُجْرَةِ فَخَرَجَتْ إِحْدَاهُمَا وَقَدْ أُنْفِذَ بِإِشْفًى فِي كَفِّهَا فَادَّعَتْ عَلَى الأُخْرَى فَرُفِعَ إِلَى ابْنِ عَبَّاسٍ۔ فَقَالَ ابْنُ عَبَّاسٍ: قَالَ رَسُولُ اللَّهِ ﷺ «لَوْ يُعْطَى النَّاسُ بِدَعْوَاهُمْ، لَذَهَبَ دِمَاءُ قَوْمٍ وَأَمْوَالُهُمْ۔» ذَكِّرُوهَا بِاللَّهِ وَاقْرَءُوا عَلَيْهَا {إِنَّ الَّذِينَ يَشْتَرُونَ بِعَهْدِ اللَّهِ} فَذَكَّرُوهَا فَاعْتَرَفَتْ۔ فَقَالَ ابْنُ عَبَّاسٍ: قَالَ النَّبِيُّ ﷺ «الْيَمِينُ عَلَى الْمُدَّعَى عَلَيْهِ۔»