What A'tham mentioned in his history, the sense of which is: that when Abu Bakr began by dispatching Abu Ubayda and the armies against the Byzantines, he died before conquering their land, and the Muslims conquered it after him during the rule of Umar. Some people said to him [Umar]: Do not go out with the army; and others said: Go out with them. So he said to your father Ali (AS): What do you say, O Abu al-Hasan? Ali (AS) said to him: If you go out, you will be granted victory; and if you stay, you will be granted victory — for the Prophet, God's blessings be upon him and his family, promised us victory for Islam. He said to him: You have spoken truly, and you are the heir of the knowledge of the Messenger of God (PBUH). (Kashf al-Mahajja, vol. 1, p. 109)
Abu Bakr equipped an army and sent it against the Byzantines, but he died before the Muslims prevailed over them. When Umar took the reins of affairs, some asked him to set out himself along with the army to fight the Byzantines, while others forbade him and said: Stay in Medina! Umar consulted Ali (AS). Ali (AS) said: Whether you go or do not go makes no difference; in either case we shall be victorious, for the Messenger of God (PBUH) has promised us victory. When Umar heard this he affirmed it and said: Truly you are the heir of the Prophet's knowledge!
Ubayd Allah ibn Muhammad, Abu Muhammad, said therein, from our master Ali, your father, the Commander of the Faithful (AS): I married Fatima (AS) when I had not even a bed; yet my alms today, were they to be divided among the Banu Hashim, would suffice them all. (Kashf al-Mahajja, vol. 1, p. 182)
The Commander of the Faithful (AS) said: I was wedded to Fatima while I had not even a bed; yet today I give such alms that a single day's alms of mine, were they divided among the Banu Hashim, would make them free of need.
And he said in the book: that he (AS) made his properties into endowments, and their yield was forty thousand dinars; yet he sold his sword and said: Who will buy my sword? Had I an evening meal, I would not sell it. (Kashf al-Mahajja, vol. 1, p. 182)
The Commander of the Faithful (AS) endowed a great deal of property, and he owned so much land that its produce exceeded forty thousand dinars. Yet one day he was so poor that out of necessity, to fill his stomach, he was obliged to sell his sword. He used to say: Had I possessed that night's supper, I would not have sold it!