Sam Rivers, a founding member and bassist for the nu metal band Limp Bizkit, died on Saturday at the age of 48, his bandmates said in a social media post.

“Today we lost our brother. Our bandmate. Our heartbeat,” lead singer Fred Durst, guitarist Wes Borland, drummer John Otto and turntable DJ Lethal wrote in a tribute posted on Instagram Saturday evening.

“Sam Rivers wasn’t just our bass player — he was pure magic. The pulse beneath every song, the calm in the chaos, the soul in the sound,” the message read.