Sahih al-Bukhari 50
Narrated Abu Huraira:
One day while the Prophet (ﷺ) was sitting in the company of some people, 
     (The angel) Gabriel came and asked, "What is faith?" Allah's Messenger (ﷺ) 
     replied, 'Faith is to believe in Allah, His angels, (the) meeting with
     Him, His Apostles, and to believe in Resurrection." Then he further 
     asked, "What is Islam?" Allah's Messenger (ﷺ) replied, "To worship Allah 
     Alone and none else, to offer prayers perfectly to pay the compulsory 
     charity (Zakat) and to observe fasts during the month of Ramadan."  
     Then he further asked, "What is Ihsan (perfection)?" Allah's Messenger (ﷺ) 
     replied, "To worship Allah as if you see Him, and if you cannot 
     achieve this state of devotion then you must consider that He is 
     looking at you." Then he further asked, "When will the Hour be 
     established?" Allah's Messenger (ﷺ) replied, "The answerer has no better 
     knowledge than the questioner. But I will inform you about its 
     portents.


     1. When a slave (lady) gives birth to her master.


     2. When the shepherds of black camels start boasting and competing 
     with others in the construction of higher buildings. And the Hour is 
     one of five things which nobody knows except Allah.


     The Prophet (ﷺ) then recited: "Verily, with Allah (Alone) is the knowledge
     of the Hour--." (31. 34) Then that man (Gabriel) left and the Prophet (ﷺ) 
     asked his companions to call him back, but they could not see him. 
     Then the Prophet (ﷺ) said, "That was Gabriel who came to teach the people 
     their religion." Abu 'Abdullah said: He (the Prophet) considered all 
     that as a part of faith.
حَدَّثَنَا مُسَدَّدٌ، قَالَ حَدَّثَنَا إِسْمَاعِيلُ بْنُ إِبْرَاهِيمَ، أَخْبَرَنَا أَبُو حَيَّانَ التَّيْمِيُّ، عَنْ أَبِي زُرْعَةَ، عَنْ أَبِي هُرَيْرَةَ، قَالَ كَانَ النَّبِيُّ صلى الله عليه وسلم بَارِزًا يَوْمًا لِلنَّاسِ، فَأَتَاهُ جِبْرِيلُ فَقَالَ مَا الإِيمَانُ قَالَ ‏"‏ الإِيمَانُ أَنْ تُؤْمِنَ بِاللَّهِ وَمَلاَئِكَتِهِ وَبِلِقَائِهِ وَرُسُلِهِ، وَتُؤْمِنَ بِالْبَعْثِ ‏"‏‏.‏ قَالَ مَا الإِسْلاَمُ قَالَ ‏"‏ الإِسْلاَمُ أَنْ تَعْبُدَ اللَّهَ وَلاَ تُشْرِكَ بِهِ، وَتُقِيمَ الصَّلاَةَ، وَتُؤَدِّيَ الزَّكَاةَ الْمَفْرُوضَةَ، وَتَصُومَ رَمَضَانَ ‏"‏‏.‏ قَالَ مَا الإِحْسَانُ قَالَ ‏"‏ أَنْ تَعْبُدَ اللَّهَ كَأَنَّكَ تَرَاهُ، فَإِنْ لَمْ تَكُنْ تَرَاهُ فَإِنَّهُ يَرَاكَ ‏"‏‏.‏ قَالَ مَتَى السَّاعَةُ قَالَ ‏"‏ مَا الْمَسْئُولُ عَنْهَا بِأَعْلَمَ مِنَ السَّائِلِ، وَسَأُخْبِرُكَ عَنْ أَشْرَاطِهَا إِذَا وَلَدَتِ الأَمَةُ رَبَّهَا، وَإِذَا تَطَاوَلَ رُعَاةُ الإِبِلِ الْبُهْمُ فِي الْبُنْيَانِ، فِي خَمْسٍ لاَ يَعْلَمُهُنَّ إِلاَّ اللَّهُ ‏"‏‏.‏ ثُمَّ تَلاَ النَّبِيُّ صلى الله عليه وسلم ‏{‏إِنَّ اللَّهَ عِنْدَهُ عِلْمُ السَّاعَةِ‏}‏ الآيَةَ‏.‏ ثُمَّ أَدْبَرَ فَقَالَ ‏"‏ رُدُّوهُ ‏"‏‏.‏ فَلَمْ يَرَوْا شَيْئًا‏.‏ فَقَالَ ‏"‏ هَذَا جِبْرِيلُ جَاءَ يُعَلِّمُ النَّاسَ دِينَهُمْ ‏"‏‏.‏ قَالَ أَبُو عَبْدِ اللَّهِ جَعَلَ ذَلِكَ كُلَّهُ مِنَ الإِيمَانِ‏.‏