The extent of the shadow when the Messenger of Allah prayed (the noon prayer) was three to five feet in summer and five to seven feet in winter. (Using translation from Abū Dāʾūd 400)
«كَانَ قَدْرُ صَلَاةِ رَسُولِ اللَّهِ ﷺ ثَلَاثَةَ أَقْدَامٍ وَفِي الشِّتَاءِ خَمْسَةُ أَقْدَامٍ إِلَى سَبْعَةِ أَقْدَامٍ»