What is the authenticity of the narration reported from Ibn Sirin that the Mahdi is better than Abu Bakr and Umar, and that he almost surpassed the prophets?

The mentioned narration has not been found and is incorrect. Muslim scholars have unanimously agreed that the best of creation after the prophets are the companions of the Messenger of Allah, peace and blessings be upon him, and the best of the companions are the Rightly Guided Caliphs, and the best of the Caliphs are Abu Bakr and Umar. The texts of revelation and the sayings of the righteous predecessors attest to this.