Al-Aswad bin Hilal (may Allah have mercy on him) narrates from Sayyiduna Mu'adh bin Jabal (may Allah be pleased with him) that he said that the Messenger of Allah (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: "That you worship Him and do not associate anything with Him. Do you know what the right of the servants upon Allah is if they do that? That He does not punish them."
Hadith Referenceالمعجم الكبير للطبراني / باب الميم / 17455