Hayden clinched a permanent switch to Newcastle on Monday, where he hopes to become a key part of Rafa Benitez's side, who are targeting promotion back to the Premier League.
Hayden has been at Arsenal since he was a youngster and captained the under-21 side. He had hoped to establish himself as a first team player alongside Jack Wilshere, but it was not meant to be.
Nonetheless his pal reached out to him publicly to wish him all the best.
Hayden made his debut for Arsenal in the League Cup tie in 2013, a game in which Wilshere did not feature, but he did play alongside established names like Per Mertesacker and Nacho Monreal.