Hadith: Whoever dies while not associating anything with Allah will enter Paradise, and whoever dies while associating anything with Allah will enter Hellfire

عَنْ جَابِرٍ رضي الله عنه قَالَ:
أَتَى النَّبِيَّ صَلَّى اللهُ عَلَيْهِ وَسَلَّمَ رَجُلٌ فَقَالَ: يَا رَسُولَ اللهِ، مَا الْمُوجِبَتَانِ؟ فَقَالَ: «مَنْ مَاتَ لَا يُشْرِكُ بِاللهِ شَيْئًا دَخَلَ الْجَنَّةَ، وَمَنْ مَاتَ يُشْرِكُ بِاللهِ شَيْئًا دَخَلَ النَّارَ»
[صحيح] - [رواه مسلم] - [صحيح مسلم: 93]

Jābir (may Allah be pleased with him) reported:
A man came to the Prophet (may Allah’s peace and blessings be upon him) and said: "O Messenger of Allah, what are the two imperatives?" He said: "Whoever dies while not associating anything with Allah will enter Paradise, and whoever dies while associating anything with Allah will enter Hellfire."
[Authentic hadith] - [Narrated by Muslim] - [Sahih Muslim - 93]

Explanation

A man asked the Prophet (may Allah's peace and blessings be upon him) about the two traits: one that makes entering Paradise due, and one that makes entering Hellfire due. In response, the Prophet (may Allah's peace and blessings be upon him) said that the trait that makes entering Paradise due is that a person should die while worshiping Allah alone and associating nothing with Him; and the trait that makes entering Hellfire due is that a person should die while associating anything with Allah, by ascribing to Him a partner or equal in His divinity or lordship or His names and attributes.

Benefits from the Hadith

1. It points out the merit of monotheistic belief and that, whoever dies as a believer, not associating anything with Allah, that person will enter Paradise.
2. It demonstrates the graveness of polytheism and that whoever dies while associating anything with Allah will enter Hellfire.
3. Muslim sinners are subject to Allah's will: if He wills, He may punish them; and if He wills, He may forgive them. Then, they will end up in Paradise.