First Abu Bakr ra verifies his own credibility with Uthman ra; to confirm that he has always told the truth. Then he goes to the topic (orchestrated carefully bc of the gravity of the topic), to prepare Uthman ra for what he is about to say. It creates curiosity. It creates a conversational contract, that Uthman ra is now very engaged and eager to hear what Abu Bakr ra has to say. It is a carefully, thoughtful and intentional way to speak about something that may be considered controversial. That Abu Bakr ra is not know to ever create problems or drama ever.