Is the Hadith: "O Messenger of Allah, when will the war end? He (peace and blessings be upon him) said: When the vessel is filled with 'Allah is sufficient for us, and [He is] the best Disposer of affairs'" authentic or present [in the Sunnah]?

There is no authentic hadith (definition) with this exact wording attributed to the Prophet, peace and blessings be upon him. However, it is authentically reported that he said, "Sufficient for us is Allah, and [He is] the best Disposer of affairs," during the Battle of Hamra' al-Asad, when it was said to him that Quraysh had gathered to return against them. Then the verse was revealed: "Those to whom people said, 'Indeed, the people have gathered against you, so fear them.' But it only increased them in faith, and they said, 'Sufficient for us is Allah, and [He is] the best Disposer of affairs.'" And Abraham, peace be upon him, said it when he was thrown into the fire.