This statement kills those who use to argue that Imam Ahmed-gurey was Marehan.Read here.
''The army camped around the city (Harar; my own barracks), with each tribe being kept apart from the others. The tribe of the Marraihan was, however, wavering. Their chieftain was a man fond of intrigue and procrastination. Extremely wily, he loved double-dealing and swindles. The imam organised some of his soldiers and went to the Marraihan and confronted
Hirabu and his tribe and said to him: 'Why are you lagging behind in coming on the jihad? Hirabu complained about his plight, and excused himself on the grounds of his poverty-stricken state.
The imam accepted his excuse, and then said to him: 'But no good will come to you from just wishing (that things will improve). Thereupon Hirabu appointed his nephew to command the Marraihan and they rallied around the imam -ninety cavalry and more than seven-hundred footsoldiers- with Hirabu bringing up the rear. The imam went back to his city of Harar, taking the tribe of Marraihan with him.''
The pronoun "his" was used for Hirabu and excluded the Imam from belonging to the Marehans.