Sunan an-Nasa'i, Hadith 1869 ⓘ
It was narrated that Thabit said: "I heard Anas say: 'The Messenger of Allah said: True patience is that which comes at the first blow."'
أَخْبَرَنَا عَمْرُو بْنُ عَلِيٍّ، قَالَ حَدَّثَنَا مُحَمَّدُ بْنُ جَعْفَرٍ، قَالَ حَدَّثَنَا شُعْبَةُ، عَنْ ثَابِتٍ، قَالَ سَمِعْتُ أَنَسًا، يَقُولُ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم " الصَّبْرُ عِنْدَ الصَّدْمَةِ الأُولَى " .
also referenced under: Book 21, Hadith 52 (In-Book) & Volume 3, Book 21, Hadith 1870 (DarusSalam)