first of all as a muslim i have great respect for all sahaba whether they were from quraish, ansar or from any other tribe. further we have got no reason to have such kind of opinion about them that they did not trust each other (i humbly request u not to forget their roles they have played in the propogation of islam… probably u have developed such kind of opinion about them as the most authentic book of 12ers “Asool e Kafi” does not highlight the role of the sahaba other than hazrat ali and his followers. not much detail about the wars of badr, uhad , ahzab and incident of hudaybia , bair e muana… so if u dont read about their contribution how can u praise them).
2ndly ur statement contains obvious contradiction. Prophet himself was from quraish and hazrat ali too.
if ansar wud mistrust quereshi’s how they wud become willing to give oath to hazrat ali.