Sahih al-Bukhari 39
Narrated Abu Huraira:
The Prophet (ﷺ) said, "Religion is very easy and whoever overburdens 
     himself in his religion will not be able to continue in that way. So 
     you should not be extremists, but try to be near to perfection and 
     receive the good tidings that you will be rewarded; and gain strength 
     by worshipping in the mornings, the afternoons, and during the last hours of the nights." (See Fath-ul-Bari, Page 
     102, Vol 1).
حَدَّثَنَا عَبْدُ السَّلاَمِ بْنُ مُطَهَّرٍ، قَالَ حَدَّثَنَا عُمَرُ بْنُ عَلِيٍّ، عَنْ مَعْنِ بْنِ مُحَمَّدٍ الْغِفَارِيِّ، عَنْ سَعِيدِ بْنِ أَبِي سَعِيدٍ الْمَقْبُرِيِّ، عَنْ أَبِي هُرَيْرَةَ، عَنِ النَّبِيِّ صلى الله عليه وسلم قَالَ ‏
"‏ إِنَّ الدِّينَ يُسْرٌ، وَلَنْ يُشَادَّ الدِّينَ أَحَدٌ إِلاَّ غَلَبَهُ، فَسَدِّدُوا وَقَارِبُوا وَأَبْشِرُوا، وَاسْتَعِينُوا بِالْغَدْوَةِ وَالرَّوْحَةِ وَشَىْءٍ مِنَ الدُّلْجَةِ ‏"‏‏.‏