This article originally appeared on People.
The 38-year-old singer shared a post on Instagram Monday explaining why he did not perform in Manchester despite being announced as part of the star-studded lineup.
“So happy to see that last night’s concert in Manchester proved that love always prevails,” he captioned a photo of the stage. “I would have loved to be there but it was my son’s first day at Camp Kudzu, one of the few summer camps for kids living with diabetes. This was an important day for him and for myself as a proud father.”
He concluded his message, “Stay strong UK.”
The Voice alum has previously spoken out about his 9-year-old son Usher V (aka “Cinco”)’s struggle with type 1 diabetes and used his platform to advocate for a cure for the disease, which prevents the body from producing insulin.
“A child that every day has to prick himself and has to be cautious of what he eats and also to carry this disorder around — that really is the type of bravery that we all aspire to have,” Usher told PEOPLE at the 2015 JDRF‘s Promise Ball, which aimed to raise awareness and money for research and a cure.
While he’s inspired by his son (with ex Tameka Foster), the “I Don’t Mind” singer says it’s been hard on him too.
“There’s been some difficult moments,” he said, but “having dealt with it on a daily basis, I have a great deal of understanding of what people have to deal with. It’s personal.”