The Plague of 'Amwas

Mu'adh once rode behind the Prophet ﷺ on a donkey. The Prophet ﷺ asked him, "Do you know Allah's right over His servants, and the servants' right over Allah?" Mu'adh said Allah and His Messenger knew best. "Allah's right over His servants is that they worship Him and associate nothing with Him; and their right over Allah is that He will not punish whoever associates nothing with Him." Mu'adh asked if he might tell people the good news. "Do not," said the Prophet ﷺ, "lest they rely on it alone" (Sahih al-Bukhari 2856; Sahih Muslim 30).

Mu'adh kept that report to himself, until the hour of his death, when he told it, fearing the sin of hiding knowledge (Sahih al-Bukhari 128; Sahih Muslim 32). That detail shows how seriously he took both the duty to teach and the care required in choosing when.

In 18 AH a plague struck the Muslim army in al-Sham, near 'Amwas. Abu 'Ubaydah ibn al-Jarrah, the commander, died of it and named Mu'adh to succeed him, and Mu'adh himself soon died, still in his thirties, in the Jordan valley (sources differ on his exact age). Reports say he met the sickness with patience and longing for Allah, but their chains are not all strong.