Amr bin Maymun al-Awdi (may Allah have mercy on him) narrates from Sayyiduna Mu'adh bin Jabal (may Allah be pleased with him); he said: I was riding behind the Prophet (peace and blessings be upon him), and he (peace and blessings be upon him) said: "O Mu'adh! Do you know what the right of Allah upon His servants is, and what the right of the servants upon Allah is? The right of Allah upon the servants is that they worship Him and do not associate anything with Him, and the right of the servants upon Allah is that He does not punish whoever dies without associating anything with Him."
Hadith Referenceالمعجم الكبير للطبراني / باب الميم / 17391