Bob Weir, the singer, songwriter and guitarist best known as a founding member of the Grateful Dead, has passed away at the age of 78, his family shared on Instagram Saturday.

“It is with profound sadness that we share the passing of Bobby Weir,” Weir’s family wrote in a statement. “He transitioned peacefully, surrounded by loved ones, after courageously beating cancer as only Bobby could. Unfortunately, he succumbed to underlying lung issues."

The family also said Weir would "forever be a guiding force whose unique artistry reshaped American music."

“His work did more than fill rooms with music; it was warm sunlight that filled the soul, building a community, a language, and a feeling of family that generations of fans carry with them. Every chord he played, every word he sang was an integral part of the stories he wove. There was an invitation: to feel, to question, to wander, and to belong,” the statement said.