Jim Kelly Pens Heartfelt 'Thank You' For Support During Grandson's Health Battle

Jim Kelly's newborn grandson returned home earlier this week after spending 38 days in the hospital with "unexpected medical complications" ... and the legendary Buffalo Bills quarterback is now taking time to thank everyone who supported them on their journey -- saying, "We will never forget you."

Kelly and his wife, Jill, shared the lengthy statement on their Instagrams with a carousel of photos featuring their daughter, Erin, and her son, Beau ... and took the opportunity to praise the talented staff at Golisano Children's Hospital for their hard work.

"You listened to our countless questions and answered them with patience, grace, and compassion. You cared not only for Beau, but for all of us," the Kellys said.

They also gave a special shoutout to a man named Albert ... who worked the desk at the facility.

"Your smile, your questions about how we were doing, and your willingness to help meant more than you will ever know," he wrote. "You have no idea the kind of impact you had on all of us."

The Kellys wrapped it up by thanking everyone who "fervently prayed" for their grandson ... saying it helped remind them they were not alone.

"You carried us in ways you may not realize, and we are forever grateful."

While Beau is home ... they noted the journey is far from over and "more healing is needed."