What does the statement that ʿUbayd ibn ʿUmayr was born in the Prophet’s era establish?

Historical Examples of Muʿanʿan Transmission and the Conclusion of Muslim’s Introduction

• Explicit evidence he heard this report from Umm Salamah
• Chronological possibility of contact with the Companion generation
• Necessary direct hearing from the Prophet
• Mass transmission of all his routes from Umm Salamah