From Sahih Bukhari (Hadith 5786):
Narrated Abu Juhaifa:I saw Bilal bringing a short spear (or stick) and fixing it in the ground, and then he proclaimed the Iqama of the prayer, and I saw Allah's Messenger (ﷺ) coming out, wearing a cloak with its sleeves rolled up. He then offered a two-rak`at prayer while facing the stick, and I saw the people and animals passing in front of him beyond the stick
Reference: Bukhari 5786