We were sitting with Messenger of Allah (ﷺ). Abu Bakr and 'Umar (May Allah be pleased with them) were also there among the audience. In the meanwhile Messenger of Allah (ﷺ) got up and left us. We waited long for his return: When we were worried about his safety, and got scared, we got up. I, therefore, went out to look for Messenger of Allah and came to a garden which belonged to the Ansar. He (ﷺ) said to me "Go and give glad tidings of Jannah to anyone who testifies 'La ilaha illallah (There is no true god except Allah),' being whole-heartedly certain of it"

[Muslim].