They found in the books, or in a document, of Saad bin Ubada that the Messenger of Allah ﷺ ruled based on an oath together with a single witness.
حدثنا أبو سلمة الخزاعي حدثنا سليمان بن بلال عن ربيعة بن أبي عبد الرحمن
أنهم وجدوا في كتب أو في كتاب سعد بن عبادة أن رسول الله ﷺ قضى باليمين مع الشاهد
Its isnad is hasan, on account of Ismail bin Amr bin Qays and his father Amr bin Qays. As for Ismail, Abu Hatim said of him, "A shaykh whose standing is that of truthfulness." As for his father, some considered him unknown, among them Ibn Hajar in Tajil, while others accepted him.The hadith was narrated by Tirmidhi 3/618, no. 1344, from Jabir, and from Ali as a mursal report, and from Abu Hurairah. Regarding the hadith of Abu Hurairah he said, "Hasan gharib," and he said nothing about the hadith of Jabir, and regarding the hadith of Ali he said, "It is more sahih than the hadith of Jabir." Then he said, "This is what is acted upon according to Malik, Shafii, Ahmad, and Ishaq."I say, this is also a position held among the Hanafis, but Abu Hanifah and the majority of his followers do not permit this and declared this hadith daif. See Sunan Ibn Majah 2/793, no. 2368, which was already presented as sahih. See 2969 and 2888.