Abu Rafi' narrates from Sayyiduna Abu Hurayrah (may Allah be pleased with him) that when both parties present one witness each, I will cast lots between them, because the Prophet (peace and blessings be upon him) also did so.
(b) Abu Rafi' narrates from Sayyiduna Abu Hurayrah (may Allah be pleased with him) that two people came to the Prophet (peace and blessings be upon him) with a dispute. Neither of them had witnesses. The Prophet (peace and blessings be upon him) said: "Cast lots between yourselves for the oath."
Imam al-Shafi'i (may Allah have mercy on him) said: It will be divided equally between them, because the proofs of both are equal.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الدعوى والبينات / 21238