بُلُوغُ الْمَرَامِ
Bulugh al-Maram 157
The Book of Prayer
وَعَنْ رَافِعِ بْنِ خَدِيجٍ قَالَ: { كُنَّا نُصَلِّي اَلْمَغْرِبَ مَعَ اَلنَّبِيِّ - صلى الله عليه وسلم -فَيَنْصَرِفُ أَحَدُنَا وَإِنَّهُ لَيُبْصِرُ مَوَاقِعَ نَبْلِهِ } مُتَّفَقٌ عَلَيْهِ [1] .
Narrated Rafi' bin Khadij (RA): We used to offer the Maghrib prayer with Allah's Messenger (ﷺ) and then one of us would go (out of the mosque) and be able to see the spot his would fall at. [Agreed upon].
Sunnah.com reference: Book 2, Hadith 7