It wasnarrated that Ibn 'Umar said:
"A small spear (Harbah) would bebrought out to the Prophet (ﷺ) when he was travelling; he wouldplant it (in the ground) to perform prayer while facing it." (FR)
English reference (FR): Vol. 1, Book 5, Hadith 941 (FR)
Arabic reference (FR): Book 5, Hadith 994 (FR)