Conversation so far:
What happened during the expedition of Tabuk?
At Tabuk the standard of the army was entrusted to Abu Bakr.
When did the expedition happen?
630 AD.
Where was Tabuk located?
Tabuk on the Syrian border.

Question: What did Abu Bakr do during the expedition?
Self-contained rewrite: What did Abu Bakr do during the expedition of Tabuk?