Hadith 215

“I was riding behind the Prophet (ﷺ) and he called out, 'Mu'adh!' I said: At your service and at your pleasure. Then he said the same thing three times, then asked: 'Do you know what is Allah's right on His slaves? I said No; he (ﷺ) said, ‘they should worship Him and not associate anything with Him.' …”