when Al Mansour built Baghdad, he spent too much on its construction. so. he though to demolish the palace of Kisra / the hall in which he used to sit and rule(king of fors/persians at that time) and use its ruins. he consulted Khaled about this. Khaled told him not to do this because it's Islam's aya(sign) and the prayer of Ali Ibn Abi Taleb(the place where Ali Ibn Taleb prayed) and what is used to demolish it can be used to make it more useful. Al Mansour replied: Khaled you refused because of your tendence(liking) to Al Ajam(persian)