userMessages(..., status, width = 4)

if (interactive()) {
 library(shiny)
 library(bs4Dash)
 shinyApp(
  ui = bs4DashPage(
    bs4DashNavbar(),
    bs4DashSidebar(),
    bs4DashControlbar(),
    bs4DashBody(
     userMessages(
      status = "success",
      userMessage(
       author = "Alexander Pierce",
       date = "20 Jan 2:00 pm",
       src = "https://adminlte.io/themes/AdminLTE/dist/img/user1-128x128.jpg",
       side = NULL,
       "Is this template really for free? That's unbelievable!"
      )
     )
    ),
    title = "user Message"
  ),
  server = function(input, output) { }
 )
}