Hadith: The right of Allah upon His servants is that they worship Him and associate none with Him

عَنْ مُعَاذٍ رَضِيَ اللَّهُ عَنْهُ، قَالَ: كُنْتُ رِدْفَ النَّبِيِّ صَلَّى اللهُ عَلَيْهِ وَسَلَّمَ عَلَى حِمَارٍ يُقَالُ لَهُ عُفَيْرٌ، فَقَالَ: «يَا مُعَاذُ، هَلْ تَدْرِي حَقَّ اللَّهِ عَلَى عِبَادِهِ، وَمَا حَقُّ العِبَادِ عَلَى اللَّهِ؟»، قُلْتُ: اللَّهُ وَرَسُولُهُ أَعْلَمُ، قَالَ: «فَإِنَّ حَقَّ اللَّهِ عَلَى العِبَادِ أَنْ يَعْبُدُوهُ وَلا يُشْرِكُوا بِهِ شَيْئًا، وَحَقَّ العِبَادِ عَلَى اللَّهِ أَنْ لا يُعَذِّبَ مَنْ لا يُشْرِكُ بِهِ شَيْئًا»، فَقُلْتُ: يَا رَسُولَ اللَّهِ أَفَلاَ أُبَشِّرُ بِهِ النَّاسَ؟ قَالَ: «لا تُبَشِّرْهُمْ، فَيَتَّكِلُوا».
[صحيح] - [متفق عليه]

Mu‘ādh (may Allah be pleased with him) reported: I was riding behind the Prophet (may Allah’s peace and blessings be upon him) on a donkey called ‘Ufayr. The Prophet (may Allah’s peace and blessings be upon him) asked: "O Mu‘ādh, do you know what Allah's right upon His servants is, and what the right of His servants upon Him is?" I replied: "Allah and His Messenger know best." He said: "Allah's right upon His servants is that they should worship Him and associate no partners with Him. And the right of the servants upon Allah is that He should not punish whoever associates no partners with Him." I said: "O Messenger of Allah, should I not inform the people of this good news?" He said: "Do not inform them of it, lest they depend on it solely."
Sahih/Authentic. - [Al-Bukhari and Muslim]

Explanation

Mu‘ādh ibn Jabal (may Allah be pleased with him) reported: I was riding behind the Prophet (may Allah’s peace and blessings be upon him) on a donkey called ‘Ufayr. He said: O Mu‘ādh, do you know what the right of Allah upon His servants is? That is what He has ordained and made due upon them. And what the right of the servants upon Allah is? That is the reward and recompense He has promised them, and His promise is true. He, Exalted be He, ordains whatever He wishes upon Himself, out of His grace and bounty. Thereupon, Mu‘ādh said: Allah and His Messenger know best. So, the Prophet (may Allah’s peace and blessings be upon him) said: The right of Allah upon His servants is that they should worship Him alone and ascribe no partners with Him. And the right of the servants upon Allah is that He should not punish those who believe in His oneness and associate no partners with Him - out of Allah's grace and mercy toward His servants. Thereupon, Mu‘ādh asked: O Messenger of Allah, should I convey this good news to people and tell them that Allah will admit into Paradise everyone who dies while associating no partners with Him? The Prophet (may Allah’s peace and blessings be upon him) instructed him not to tell them, lest they would cease to work and would depend solely on this statement; so, he should let them do good deeds and work hard.