"We have a gig in 2 weeks and I'm not doing it without you. YOU'RE BEING RIDICULOUS @Joan Rivers," the 43-year-old comedian tweeted Sunday.
Silverman's post came a day after 81-year-old Rivers was put on life support at Mount Sinai hospital in New York following her cardiac arrest on Thursday. The comedian was undergoing a scheduled throat surgery when she stopped breathing and was rushed to the hospital last week.
Rivers was put into a medically induced coma upon arriving to the hospital and is currently depending on life support machines to stay alive. Sources say her family will have to determine soon whether to pull her off the machines, although insiders told the New York Daily News Melissa Rivers is "in denial" about her mother's health.
@joan_rivers thinking of you and your family today. You are in my prayers.— Mike Tyson (@MikeTyson) August 31, 2014
Please keep Joan Rivers in your prayers— Rihanna (@rihanna) September 2, 2014