Once Mu'âdh was riding behind Allâh's Messenger (ﷺ) as a companion rider. Allâh's Messenger (ﷺ) said, O Mu'adh (bin Jabal)." replied, Labbaik and Sa'daik. O Allâh's Messenger (ﷺ)! " Again the Prophet (ﷺ) said, "O Mu'adh! " Mu'adh said thrice, Labbaik and Sa'daik, O Allâh's Messenger (ﷺ)! " Allâh's Messenger (ﷺ) said, "There is none who testifies sincerely from his heart that La ilaha ill-Allah, wa anna Muḥammad- ar-Rasûl Allâh (none has the right to be worshipped but Allâh and Muḥammad (ﷺ) is the Messenger of Allâh), except that Allâh will save him from the Hell-fire." Mu'adh said, "O Allâh's Messenger (ﷺ)! Should I not inform the people about it so that they may have glad tidings?" He replied, "When (the people hear about it), they will solely depend on it." Then Mu'adh narrated the above mentioned Hadith just before his death, being afraid of committing a sin (by concealing the knowledge). [1:130-O.B.]