TMZ.COM is reporting that The Iron Sheik passed away in his sleep due to a cardiac arrest according to his death certificate.

The document also stated that the WWE Hall of Famer suffered from congestive heart failure as well as hypertension before he passed away. The 81-year-old’s death was ruled natural.

Sheik passed away on June 7 and tons of tributes followed on social media to honor the legendary former WWE champion.