and this course was applauded by al-Sindi and ʿAli ibn ʿIsa ibn Mahan; then Harthama and Rafiʿ ibn al-Layth ibn Nasr ibn Sayyar were reconciled and travelled to al-Maʾmun, Tahir ibn al-Husayn accompanying them.

Later al-Amin sent a request to al-Maʾmun that his own son Musa be placed before al-Maʾmun in the line of succession, granting the boy the honorific “the One Who Speaks the Truth.” Al-Maʾmun refused, but he won over the envoy, who secretly swore allegiance to him and kept up a clandestine correspondence; that envoy was al-ʿAbbas ibn Musa ibn ʿIsa ibn Musa (1).

When al-Amin learned of al-Maʾmun’s resistance, he struck his brother’s name from the public prayers and demanded the document that al-Rashid had written and hung upon the Kaaba as a covenant between the two brothers; he tore it to pieces.

The men of sound judgment rebuked him, yet he would not listen until Khazim ibn Khuzaymah said:

“He who lies to you will never counsel you sincerely,
and he who tells you the truth will never betray you.
Do not embolden the commanders to depose you, lest they depose you;
do not drive them to break their oaths, for the traitor is ever humbled
and the oath-breaker ever forsaken.”

Still he paid no heed, took the pledge of allegiance for Musa as heir, and appointed a vizier on his behalf.

When al-Maʾmun learned of this, he deposed his brother and adopted the title Commander of the Faithful. As for Ibn Mahan, al-Amin equipped him, granted him two hundred thousand dinars, and gave him a silver shackle with which—so he claimed—he would bind al-Maʾmun.

Al-Amin reviewed his troops at Nahrawan, while Tahir advanced with four thousand men. They met in battle: Ibn Mahan was killed and his army scattered, yet al-Amin remained engrossed in diversion and play. He therefore dispatched another army, regretted his removal of al-Maʾmun, and his commanders began to covet his position.

Tahir and al-Amin’s forces then faced one another at Hamadhan. Many were slain and the calamity became grave. Al-Amin’s army entered the city, whereupon Tahir laid siege to them; their commander came down to Tahir under a pledge of safety in the year 195 AH (2).