Ṣaḥīḥ Muslim
صَحِيحُ مُسْلِم
Considered one of the two most authentic collections of aḥādīth, second only to Bukhārī. Full name: al-musnau al-ṣaḥīḥ al-mukhtaṣar bi-naql al-ʿadli ʿani al-ʿadli ilā Rasūlillāh ﷺ (المسند الصحيح المختصر بنقل العدل عن العدل إلى رسول الله ﷺ) (The authentic, concise musnad transmitted by a trustworthy narrator from a trustworthy narrator back to the Messenger of Allah ﷺ). It is commonly known as Ṣaḥīḥ Muslim (صحيح مسلم) (The Authentic Collection by Muslim). Sources: sunnah.com for the Arabic text and English translation. The English translation has been improved by myself and other contributors.
Random ḥadīth in Muslim
Command to fight hypocrisy and disobedience to the Sunnah after it has spread after the Prophet ﷺ
The Messenger of Allah ﷺ said: “There is no prophet whom Allah sent among a nation before me except that he had from his nation hawārīs (devoted disciples) and aṣḥāb (companions) who would follow his way and adhere to his command. Then after them there would come successors who say what they do not do, and do what they are not commanded to do. Whoever strives against them with his hand is a believer; whoever strives against them with his tongue is a believer; and whoever strives against them with his heart is a believer, and beyond that there is not even a mustard seed’s weight of faith.”
أَنَّ رَسُولَ اللَّهِ ﷺ قَالَ: «مَا مِنْ نَبِيٍّ بَعَثَهُ اللَّهُ فِي أُمَّةٍ قَبْلِي إِلاَّ كَانَ لَهُ مِنْ أُمَّتِهِ حَوَارِيُّونَ وَأَصْحَابٌ يَأْخُذُونَ بِسُنَّتِهِ وَيَقْتَدُونَ بِأَمْرِهِ، ثُمَّ إِنَّهَا تَخْلُفُ مِنْ بَعْدِهِمْ خُلُوفٌ، يَقُولُونَ مَا لاَ يَفْعَلُونَ وَيَفْعَلُونَ مَا لاَ يُؤْمَرُونَ، فَمَنْ جَاهَدَهُمْ بِيَدِهِ فَهُوَ مُؤْمِنٌ وَمَنْ جَاهَدَهُمْ بِلِسَانِهِ فَهُوَ مُؤْمِنٌ، وَمَنْ جَاهَدَهُمْ بِقَلْبِهِ فَهُوَ مُؤْمِنٌ وَلَيْسَ وَرَاءَ ذَلِكَ مِنَ الإِيمَانِ حَبَّةُ خَرْدَلٍ».