The first incident (with a Shi'ee):

The Shi'ee claimed that we (Ahlus-Sunnah) don't love Hassan and Hussein (the Prophet's grandsons) رضي الله عنهما because we don't narrate from them. Response: Firstly, The Prophet ﷺ passed away while both of them were 6-7 years old approximately. Secondly, Abu Hurairah رضي الله عنه reported more hadiths than Umar رضي الله عنه, even though we hold Umar to be better and more virtuous than Abu Hurairah. So virtue is not merely based on the number of narrations one has, but rather virtue is based on the Prophet's testimony ﷺ. The Shi'ee realised he was in the wrong.