حبیب السیر 3: Isma'il bin Násiru-d dín.

3

When Násiru-d dín Subuktigín tied up his travelling apparatus for another world, Amír Isma'íl, by virtue of the will of his father, ascended the throne at Balkh, the tabernacle of the faithful; he made great endeavours to attract the affections and conciliate the hearts of the people; he opened the treasury of Amír Subuktigín, and distributed much money among the soldiers. The report of this came to the ears of his elder brother Saifu-d daula Mahmud, at Naishapur, who sent Amir Isma'il a letter to this effect: "You are the dearest to me of all men. Whatever you may require of the country or of the revenue is not denied; but a knowledge of the minute points in the affairs of government, a period of life reaching to an advanced age, experience in the times, and perseverance and durability of wealth, possess great advantages. If you were possessed of these qualities, I would certainly subject myself to you. That which my father in my absence has bequeathed to you was bestowed because I was at a great distance, and because he apprehended calamity. Now rectitude consists in this, that, as is fitting, you should consider well, and divide between us the money and movable effects of my father, according to law and justice, and that you should give up the royal residence of Ghaznin to me. Then will I deliver over to you the country of Balkh, and the command of the army of Khurasan."
Amir Isma'il would not listen to this proposal, so Saifu-d daula Mahmud entered into a league with his uncle Baghrajik and Nasr bin Nasiru-d din Subuktigin, who was his brother, and leaving Naishapur, marched towards Ghaznin. Amir Isma'il also moved in that direction, and when both parties were near one another, Saifu-d daula used his virtuous endeavours to prevent Isma'il from engaging in battle, and tried to make a reconciliation, but he could not succeed; and after lighting the flame of battle, and the employment of weapons, and inflicting of blows, Amir Isma'il was defeated. He took refuge in the fort of Ghaznin, and Sultan Mahmud having entered into arrangements with him, took from him the keys of the treasury, and appointed administrators over his affairs. He then marched towards Balkh.
It is related that when Amir Isma'il had been some days in the society of his brother, in the assembly of friendship, Sultan Mahmud took the occasion to ask him : "If the star of your fortune had been such that you had taken me, what would you have done with me ?" Isma'il answered, "My mind would have dictated this, that if I had obtained the victory over you, I would have shut you up in one of my forts, but I would have allowed you things necessary for repose and the enjoyment of life, as much as you could desire." Sultan Mahmud, after having obtained in that assembly the secret of the heart of his brother, remained silent ; but after some days, on some pretence, he delivered over Isma'il to the governor of Juzjan, and told him to put him into a strong fort, but to give him whatever he should ask, conducive to the repose and enjoyment of life. Amir Isma'il, as he himself had designed to act towards his brother, was shut up in that fort, and there passed the rest of his days.