Rocket.Chat/app/ui-message/client/messageThread.html

<template name="messageThread">
	<q role="button" title="{{_ " Open_thread "}}" class="thread-quote js-open-thread">
		{{> icon icon="thread" block="thread-icons"}} <div class="thread-quote__message "><span class="message-body--unstyled">{{{parentMessage}}}</span></div>
		{{# if following }}
		<div role="button" class="js-unfollow-thread" title="{{_ "Following"}}">
			{{> icon icon="bell" block="thread-icons"}}
		</div>
		{{else}}
		<div role="button" class="js-follow-thread" title="{{_ "Not_following"}}">
			{{> icon icon="bell-off" block="thread-icons"}}
		</div>
		{{/if}}
	</q>
</template>