كتاب القدر
46
The Book of Destiny
(1)
Chapter: How The Human Being Is Created, In His Mother's Womb, And His Provision, Lifespan And Deeds Are Written Down, And His Misery and Happiness
(1)
بَاب كَيْفِيَّةِ خَلْقِ الْآدَمِيِّ فِي بَطْنِ أُمِّهِ وَكِتَابَةِ رِزْقِهِ وَأَجَلِهِ وَعَمَلِهِ وَشَقَاوَتِهِ وَسَعَادَتِهِ
Sahih Muslim 2648 b

This hadith has been transmitted on the authority of Jabir b. Abdullah with the same wording (and includes these words):

" Allah's Messenger (ﷺ) said: Every doer of deed is facilitated in his action."
حَدَّثَنِي أَبُو الطَّاهِرِ، أَخْبَرَنَا ابْنُ وَهْبٍ، أَخْبَرَنِي عَمْرُو بْنُ الْحَارِثِ، عَنْ أَبِي الزُّبَيْرِ، عَنْ جَابِرِ بْنِ عَبْدِ اللَّهِ، عَنِ النَّبِيِّ صلى الله عليه وسلم بِهَذَا الْمَعْنَى وَفِيهِ فَقَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم ‏ "‏ كُلُّ عَامِلٍ مُيَسَّرٌ لِعَمَلِهِ ‏"‏ ‏.‏
Reference : Sahih Muslim 2648 b
In-book reference : Book 46, Hadith 14
USC-MSA web (English) reference : Book 33, Hadith 6403
  (deprecated numbering scheme)