Husain Abdullah returns an interception for a touchdown in a 2014 game. (Ed Zurga/AP)

Husain Abdullah, a 30-year-old free safety for the Kansas City Chiefs, announced his retirement from the NFL on Monday, citing concerns about concussions and writing that “having a sound mind will be vital in accomplishing” his future goals.

“There are numerous deciding factors in my decision, with personal health being foremost,” he wrote on Instagram. “Sitting for five weeks last year after suffering the fifth concussion of my career, I had a lot to contemplate. My goals moving forward are to be of benefit to my family, my community, my country and hopefully the world. Having a sound mind will be vital in accomplishing these goals.

“Thank you to everyone I’ve crossed paths with during my time as a player. You’ve had an impact on my life for the better. Thanks for the love and support. It’s greatly appreciated.”

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After 7 years in the NFL, I am retiring. I would like to thank the Minnesota Vikings for giving me an opportunity to make the team after going undrafted in 2008. I experienced a great deal of growth both as a football player and as a person during my 4 years in Minnesota. Thank you. The Kansas City Chiefs will forever have a special place in my heart. After sitting out of football to fulfill my Hajj Pilgrimage in 2012, The Chiefs were the first to call. The three years I spent playing for KC may have been the most enjoyable football experience in my entire life. Thank you. There are numerous deciding factors in my decision, with personal health being foremost. Sitting for five weeks last year after suffering the fifth concussion of my career, I had a lot to contemplate. My goals moving forward are to be of benefit to my family, my community, my country and hopefully the world. Having a sound mind will be vital in accomplishing these goals. Thank you to everyone I've crossed paths with during my time as a player. You've had an impact on my life for the better. Thanks for the love and support. It's greatly appreciated. #chiefskingdom #Peace✌🏿️

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Abdullah, who took 2012 off to complete a pilgrimage to Mecca, started 21 games for the Chiefs after that. An undrafted free agent in 2008, he played for four years with the Minnesota Vikings before going to KC. His brother, Hamza, was a seven-year veteran of the NFL, but did not return after the 2012 pilgrimage.

Hamza Abdullah was highly critical of Commissioner Roger Goodell and the NFL, saying that the league “was denying the fact that football causes brain damage.”

The decision by Abdullah is yet another in a trend that should trouble the NFL. Marshawn Lynch, Calvin Johnson and Jerod Mayo also have retired during this offseason. They’re all 30 or younger.