Ask Qul - Shia Sunni Dialogue - Praying open hands to close hands

Ask Qul - QA

Question : #100

Subject:	Praying open hands to close hands
Question:	Did the Prophet Muhammad pray open or close hands, and when did this division take place?
Answer:	The Prophet (s) prayed with his hands open. I do not know the exact instance that this division took place, although it is commonly known that it took place during the reign of the second caliph.

Follow Up
Question:

I recently had a short discussion about this with a Sunni sister and she said that they do that as a sign of respect, as when someone who was approaching Prophet Muhammad (saw) did before him. My questions are; is it respectful? is it obligatory or optional? And finally where and why did this tradition arise? Thank you!