كتاب الإيمان
1  
The Book of Faith
(10)
Chapter: The evidence that one who dies believing in tawhid will definitely enter paradise
(10)
باب مَنْ لَقِيَ اللَّهَ بِالإِيمَانِ وَهُوَ غَيْرُ شَاكٍّ فِيهِ دَخَلَ الْجَنَّةَ وَحَرُمَ عَلَى النَّارِ
Sahih Muslim 27 b

It is narrated either on the authority of Abu Huraira or that of Abu Sa'id Khudri. The narrator A'mash has narrated this hadith with a little bit of doubt (about the name of the very first narrator who was in direct contact with the Holy Prophet. He was either Abu Huraira or Abu Sa'id Khudri. Both are equally reliable transmitters of the traditions). He (the narrator) said:

During the time of Tabuk expedition, the (provisions) ran short and the men (of the army) suffered starvation; they said: Messenger of Allah, would you permit us to slay our camels? We would eat them and use their fat. The Messenger of Allah (ﷺ) said: Do as you please. He (the narrator) said: Then 'Umar came there and said: Messenger of Allah, if you do that (if you give your consent and the men begin to slay their camels), the riding animals would become short. But (I would suggest you to) summon them along with the provisions left with them Then invoke Allah's blessings on them (different items of the provisions) It is hoped Allah shall bless them. The Messenger of Allah replied in the affirmative. (the narrator) said: He called for a leather mat to be used as a table cloth and spread it out. Then he called people along with the remaining portions of their provisions. He (the narrator) said: Someone was coming with handful of mote, another was coming with a handful of dates, still another was coming with a portion of bread, till small quantities of these things were collected on the table cloth. He (the narrator said): Then the messenger of Allah invoked blessing (on them) and said: Fill your utensils with these provisions. He (the narrator) said: They filled their vessel to the brim with them, and no one amongst the army (which comprised of 30,000 persons) was left even with a single empty vessel. He (the narrator) aid: They ate to their fill, and there was still a surplus. Upon this the Messenger of Allah (ﷺ) remarked: I bear testimony that there is no god but Allah and I am the messenger of Allah. The man who meets his Lord without harboring any doubt about these two (truths) would never be kept away from Paradise.
حَدَّثَنَا سَهْلُ بْنُ عُثْمَانَ، وَأَبُو كُرَيْبٍ مُحَمَّدُ بْنُ الْعَلاَءِ جَمِيعًا عَنْ أَبِي مُعَاوِيَةَ، - قَالَ أَبُو كُرَيْبٍ حَدَّثَنَا أَبُو مُعَاوِيَةَ، - عَنِ الأَعْمَشِ، عَنْ أَبِي صَالِحٍ، عَنْ أَبِي هُرَيْرَةَ، أَوْ عَنْ أَبِي سَعِيدٍ، - شَكَّ الأَعْمَشُ - قَالَ لَمَّا كَانَ غَزْوَةُ تَبُوكَ أَصَابَ النَّاسَ مَجَاعَةٌ ‏.‏ قَالُوا يَا رَسُولَ اللَّهِ لَوْ أَذِنْتَ لَنَا فَنَحَرْنَا نَوَاضِحَنَا فَأَكَلْنَا وَادَّهَنَّا ‏.‏ فَقَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم ‏"‏ افْعَلُوا ‏"‏ ‏.‏ قَالَ فَجَاءَ عُمَرُ فَقَالَ يَا رَسُولَ اللَّهِ إِنْ فَعَلْتَ قَلَّ الظَّهْرُ وَلَكِنِ ادْعُهُمْ بِفَضْلِ أَزْوَادِهِمْ ثُمَّ ادْعُ اللَّهَ لَهُمْ عَلَيْهَا بِالْبَرَكَةِ لَعَلَّ اللَّهَ أَنْ يَجْعَلَ فِي ذَلِكَ ‏.‏ فَقَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم ‏"‏ نَعَمْ ‏"‏ ‏.‏ قَالَ فَدَعَا بِنِطَعٍ فَبَسَطَهُ ثُمَّ دَعَا بِفَضْلِ أَزْوَادِهِمْ - قَالَ - فَجَعَلَ الرَّجُلُ يَجِيءُ بِكَفِّ ذُرَةٍ - قَالَ - وَيَجِيءُ الآخَرُ بَكَفِّ تَمْرٍ - قَالَ - وَيَجِيءُ الآخَرُ بِكِسْرَةٍ حَتَّى اجْتَمَعَ عَلَى النِّطَعِ مِنْ ذَلِكَ شَىْءٌ يَسِيرٌ - قَالَ - فَدَعَا رَسُولُ اللَّهِ صلى الله عليه وسلم عَلَيْهِ بِالْبَرَكَةِ ثُمَّ قَالَ ‏"‏ خُذُوا فِي أَوْعِيَتِكُمْ ‏"‏ ‏.‏ قَالَ فَأَخَذُوا فِي أَوْعِيَتِهِمْ حَتَّى مَا تَرَكُوا فِي الْعَسْكَرِ وِعَاءً إِلاَّ مَلأُوهُ - قَالَ - فَأَكَلُوا حَتَّى شَبِعُوا وَفَضِلَتْ فَضْلَةٌ فَقَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم ‏"‏ أَشْهَدُ أَنْ لاَ إِلَهَ إِلاَّ اللَّهُ وَأَنِّي رَسُولُ اللَّهِ لاَ يَلْقَى اللَّهَ بِهِمَا عَبْدٌ غَيْرَ شَاكٍّ فَيُحْجَبَ عَنِ الْجَنَّةِ ‏"‏ ‏.‏
Reference : Sahih Muslim 27b
In-book reference : Book 1, Hadith 46
USC-MSA web (English) reference : Book 1, Hadith 42
  (deprecated numbering scheme)