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." (JA)
English reference (JA): Vol. 1, Book 5, Hadith 941 (JA)
Arabic reference (JA): Book 5, Hadith 994 (JA)