كتاب التوبة
50  
The Book of Repentance
(3)
Chapter: The Virtue Of Constant Dhikr, Thinking Of The Hereafter, And Remembering That Allah Is Always Watching; Permissibility Of Stopping That Sometimes, And Attending To Worldly Matters
(3)
بَاب فَضْلِ دَوَامِ الذِّكْرِ وَالْفِكْرِ فِي أُمُورِ الْآخِرَةِ وَالْمُرَاقَبَةِ وَجَوَازِ تَرْكِ ذَلِكَ فِي بَعْضِ الْأَوْقَاتِ وَالِاشْتِغَالِ بِالدُّنْيَا
Sahih Muslim 2750 b

Hanzala reported:

We were in the company of Allah's Messenger (ﷺ) and he delivered to us a sermon and made a mention of Hell-Fire. Then I came to my house and began to laugh with my children and sport with my wife. (Hanzala) further reported: I went out and met Abu Bakr and made a mention of that to him. Thereupon he said: I have done the same as you have mentioned. So we went to see Allah's Messenger (ﷺ) and said to him: Allah's Messenger, Hanzala has turned to he a hypocrite. And he (the Holy Prophet) said Show respite. And then I narrated to him the story, and Abu Bakr said: I have done the same as he has done. Thereupon he (the Holy Prophet) said: Hanzala, there is a time for worldly affairs and a time for (worship and devotion), and if your state of mind is always the same as it is at the time of remembrance of Allah, the Angels would shake hands with you and would greet you on the path by saying: As-Salamu-Alaikum.
حَدَّثَنِي إِسْحَاقُ بْنُ مَنْصُورٍ، أَخْبَرَنَا عَبْدُ الصَّمَدِ، سَمِعْتُ أَبِي يُحَدِّثُ، حَدَّثَنَا سَعِيدٌ، الْجُرَيْرِيُّ عَنْ أَبِي عُثْمَانَ النَّهْدِيِّ، عَنْ حَنْظَلَةَ، قَالَ كُنَّا عِنْدَ رَسُولِ اللَّهِ صلى الله عليه وسلم فَوَعَظَنَا فَذَكَّرَ النَّارَ - قَالَ - ثُمَّ جِئْتُ إِلَى الْبَيْتِ فَضَاحَكْتُ الصِّبْيَانَ وَلاَعَبْتُ الْمَرْأَةَ - قَالَ - فَخَرَجْتُ فَلَقِيتُ أَبَا بَكْرٍ فَذَكَرْتُ ذَلِكَ لَهُ فَقَالَ وَأَنَا قَدْ فَعَلْتُ مِثْلَ مَا تَذْكُرُ ‏.‏ فَلَقِينَا رَسُولَ اللَّهِ صلى الله عليه وسلم فَقُلْتُ يَا رَسُولَ اللَّهِ نَافَقَ حَنْظَلَةُ فَقَالَ ‏"‏ مَهْ ‏"‏ ‏.‏ فَحَدَّثْتُهُ بِالْحَدِيثِ فَقَالَ أَبُو بَكْرٍ وَأَنَا قَدْ فَعَلْتُ مِثْلَ مَا فَعَلَ فَقَالَ ‏"‏ يَا حَنْظَلَةُ سَاعَةً وَسَاعَةً وَلَوْ كَانَتْ تَكُونُ قُلُوبُكُمْ كَمَا تَكُونُ عِنْدَ الذِّكْرِ لَصَافَحَتْكُمُ الْمَلاَئِكَةُ حَتَّى تُسَلِّمَ عَلَيْكُمْ فِي الطُّرُقِ ‏"‏ ‏.‏
Reference : Sahih Muslim 2750b
In-book reference : Book 50, Hadith 15
USC-MSA web (English) reference : Book 37, Hadith 6624
  (deprecated numbering scheme)