Question

how did john byro react on seeing his white horse with aram and mourad

Answer 1

He told that it was the horse just like my horse which was stolen many days ago.

Answer 2

Mourad had stolen John Byro's beautiful white horse. John knew that who stole his horse but kept silent. 

When after three and a half months Mourad returned the horse to its actual owner, John declared that his horse was stronger than before. He was also better tempered than what he was three months ago.