Sayyiduna Mu'adh bin Jabal (may Allah be pleased with him) said: I was with the Messenger of Allah (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?" I said: Allah and His Messenger know best. He (peace and blessings be upon him) said: "The right of Allah upon the servants is that they worship Him and do not associate anything with Him." Then he said: "Do you know what the right of the servants (upon Allah) is if they do that?" I said: Allah and His Messenger know best. He (peace and blessings be upon him) said: "That He does not punish them."
Hadith Referenceالمعجم الكبير للطبراني / باب الميم / 17411