Conversation so far:
What lead up to Umar's death?
On his deathbed, Umar vacillated on his succession. Umar finally appointed a committee of six persons to choose a caliph from amongst them.
What was usamas army doing while Umar vacillated on his succession?
The only 'famous ten' left out of the committee who was still alive at the time was Saeed ibn Zaid, the cousin and brother-in-law of Umar.
Are there any other interesting aspects about the aftermath after Umar's assassination besides choosing a committee for the next caliph and leaving Saeed ibn Zaid, his cousin and brother-in-law, out of the decision?
It seemed clear that Umar's assassination had been planned by Persians residing in Medina. Infuriated by this, Umar's younger son Ubaidullah ibn Umar sought to kill all Persians in Medina.

Question: What was he too young to do?
Self-contained rewrite: What was Ubaidullah ibn Umar too young to do?