بُلُوغُ الْمَرَامِ
Bulugh al-Maram 228
The Book of Prayer
عَنْ أَبِي جُهَيْمِ بْنِ اَلْحَارِثِ - رضى الله عنه - قَالَ : قَالَ رَسُولُ اَللَّهِ - صلى الله عليه وسلم -{ لَوْ يَعْلَمُ اَلْمَارُّ بَيْنَ يَدَيِ اَلْمُصَلِّي مَاذَا عَلَيْهِ مِنْ اَلْإِثْمِ لَكَانَ أَنْ يَقِفَ أَرْبَعِينَ خَيْرًا لَهُ مِنْ أَنْ يَمُرَّ بَيْنَ يَدَيْهِ } مُتَّفَقٌ عَلَيْهِ , وَاللَّفْظُ لِلْبُخَارِيِّ . [1]
Narrated Abu Juhaim bin al-Harith (RA): Allah's Messenger (ﷺ) said: "If the person who passes in front of another person in prayer knew the magnitude of his sin, it would have been better for him to wait for forty than pass in front of him." [Agreed upon. This wording is from al-Bukhari].
Sunnah.com reference: Book 2, Hadith 94