Al-Saffah, al-Mundhir and al-Mansur

Mujahid narrates that Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) said to me: "Had I not heard that you are like us, the People of the House, I would not have narrated this hadith to you." Mujahid said: "It will remain a secret; I will not tell it to anyone whom you dislike." Ibn Abbas (may Allah be pleased with them both) said: "From us, the People of the House, there will be four (special figures): from us will be al-Saffah, from us al-Mundhir, from us al-Mansur and from us al-Mahdi." Mujahid says: I said to him: "Explain these four to me." He said: "As for al-Saffah, he will at times kill his supporters and pardon his enemy. As for al-Mundhir, he will give so much wealth that he will not consider it great in his heart, and he will withhold only a small portion of his own right. As for al-Mansur, he will be granted such victory and help over his enemy as will be half of the help given to the Messenger of Allah (peace and blessings be upon him); his (peace and blessings be upon him) enemy was struck with awe at a distance of two months' journey, while the enemy of al-Mansur will be struck with awe at a distance of one month's journey. And as for al-Mahdi, he will fill the earth with justice and fairness just as it will have been filled with oppression and injustice; grazing animals will be safe from beasts of prey, and the earth will cast out the pieces of its liver." Mujahid says: I asked: "What is meant by the pieces of its liver?" He said: "(Treasures) like pillars of gold and silver."
This hadith has a sahih (authentic) chain of narration, but the two Shaykhs did not record it.

Sayyiduna Abu Hurayrah (may Allah be pleased with him) narrates that the Prophet (peace and blessings be upon him) said: "Trials will overwhelm you like pieces of the dark night. In (the era of) those trials, the safest of people will be a man who lives on a mountain peak and subsists on the milk of his goats, or a man who holds the reins of his horse beyond the frontiers and eats from the earnings of his sword."
This hadith has a sahih (authentic) chain of narration, but the two Shaykhs did not record it.